[Larry Navarro]

Originally Posted by Steve C.

what I was getting at on my question to Larry regarding his hogged out heads was not about the impact on his vehicle track performance. Apparantly it has been proven here that Larrys torque production has been impacted with his larger runner volume heads. I was after a opinion about his "seat of the pants feel" regarding any streetability issues because of his loss in torque. Again I will suggest that there is none and his engine is smooth right off idle, and loss of part throttle power at RPM's is not detectable.

Steve I was under the inpression that the question was directed toward OTHER heads with larger volume than mine, hence the lack of experience with a collection of parts.
I feel that there are other variables that come into play with my particular combination as far as loss of low speed torque, etc.
For instance, I don't use a vacuum advance and haven't really optimized my distributor for total timing.
Also, my carb has always run on the "fat" side, I've tried different jets and PValve's to obtain a leaner condition for idle at the cost of lean cruise condition or SLIGHT off-idle stumble so I'm just shooting in the dark.
Since I lack critical tuning knowledge on the DEMON/HOLLEY carbs, I have removed the carb and sent it to "Shaker455" to give it a look and see what he can do to optimize it for my combination.
So to answer the initial question, I can say this....I feel that from the experience I have obtained through folks who use LESS and gain MORE; then YES I think my car would be a little more tolerable with less cfm and more velocity.
I wait to see how my car does when I get the carb back and on the motor.
Who knows.....I reserve the right to retract the previous statement!

[JSchmitz]

Skip, you're right, you did mention the int/exh ratio. I forgot. I chalk up your credit

I don't want to get too far off the topic. But, I read the article that Jim referenced comparing the identical iron and aluminum heads. I was very surprised that here wasn't a sizable difference. so, where did the rule, of 1 additional point of compression for AL heads, come from? Could it be that it isn't required to make the same power as iron; but will tolerate the additional point? That being the advantage of AL.

Based on Cliff's experience. It would seem that some of the things that are a factor for 4000# cars, are not for lighter cars. It goes back to my early point about combination.

[Steve C.]

Thanks Larry.

[Jim Hand]

Skip,
Unfortunately you have continually attempted to make any discussion about port volume either black or white - that it either helps or hurts!

Port volume and associated velocity are variables that change with RPM, load range, engine purpose, engine size, and a host of other technical aspects. What is ideal for one car may be totally wrong for another. You mentioned that “Ray” would laugh at smaller ports – certainly true! Ray runs very high RPM, needs lots of flow, and to get lots of flow, needs bigger ports. And another aspect – Ray’s engine is essentially a single speed engine! He launches at high RPM, runs through the ¼ at high RPM, and can therefore tune his engine (and port size and flow) for max power at high RPM and relatively narrow RPM range. But the same rules apply to Ray – if he makes his ports too large in relation to the amount of air his engine needs and uses, he will lose power. Our presently available heads may not allow him to run too much volume, but that does not change the physics of this subject.

So it is not a simple question of little ports are good, and big ports are bad, or vice versa. Rather, it is obtaining the optimum balance of port size/velocity to complement the engine and the load it sees. For example, I have known for years that the 165 cc ports on my 64 heads were limiting peak airflow, and therefore peak power. But I also know that peak power is only one of the factors in running well at a track.

Accordingly, I have traded some top end power loss, due to small ports, for superior torque in the low and mid range. And a bonus to that is not only does it help drag strip performance but also improves throttle feel and response on the street. Skip, you have posted numerous times that “no one else with similar engine setup” runs as well as I do- remember? Then you had to acknowledge that maybe Floyd did, and then we saw Cliff doing it as well. It turns out that all those other cars were and are not setup like ours. And especially with the heads! And I continue to be competitive against any comparable weight car with any heads or port size!

And I know and fully understand that if I wanted to effectively run higher RPM, I will need both added airflow, and the larger ports to obtain that flow. But I also know that when that approach is used, low and early mid range power begins to suffer. That is not a problem as long as I understand it and modify the rest of the car to work with it.

When we want and need a wide range of power, and want to make the most possible power, we have to effectively “average” the port volume and air velocity to obtain the best total or average power within the RPM range we want. And a car that must start from essentially idle, run to some upper end RPM, shift back to a lower RPM, etc., is totally different from Ray’s race car. And the engine parameters must be selected and setup accordingly. So there is no one size fits all in port volume and velocity, just as there is not with cams, intakes, carbs, and all the rest of the parts that make up a good running vehicle.

We have always stated that new better flowing heads will usually help performance over stock heads, and that includes the even bigger port E heads. But we have also said that some of those heads would work even better with smaller ports. And sure enough, Cliff’s dyno tests of the smaller port KRE heads against the 216 E heads confirmed that. And my at-the-track five times tests clearly proved it.

So a simple statement that since Cliff ran better with the new larger port heads, that alone proves that larger ports don’t affect power, is an incomplete and misleading approach. Also, the fact that less low RPM power might improve traction and therefore is somehow “better” is also misleading. We are talking about power production, and not chassis or tire setups. If there is less power, it is caused by something in the engine!

Exactly as I stated at various meetings when the KRE heads were introduced, in my book, and countless times on this and other boards, the new KRE heads are an excellent design and will add power compared to any stock type unported or minimum ported heads. And I have also said, and it has been proven on the KRE dyno, the smaller 185 cc ports of the KRE heads are an improvement over the 216 of the E heads for developing better mid range power. The E heads work great, make lots of power, can spin tires, and also will help over any stock iron head. But the larger port volume does have an adverse affect on power production at lower RPM.

I have also proven that my even smaller ports of 170 can add power over the KRE 185 cc ports, and do it with less airflow! The proof is in the performance numbers quoted above. Some of you might have noticed the small formula I mentioned about evaluating flow vs volume. It came to us from the chief head designer at Chrysler Corp:

“A good porting job or head design will always add greater flow increase then port volume increase!” Here is how it breaks down with three heads I am very familiar with:

Assuming stock heads flow 210 cfm @ 28”, and measure 153 cc port volume, and that seems to be close to what most measure:

My 6X heads improved from 210 to 266 for a percentage gain of 26.7%
My 6X port volume increased from the stock 153 to 170 for a percentage enlargement of 11 % - an excellent ratio – 26.7 to 11.

KRE heads improved from 210 to about the same 266 for a similar gain of 26-27%
KRE heads increased volume from 153 to 185 for a percentage enlargement of 21% - still a good ratio. – 26 to 21.

E heads improved flow from 210 to 273 for a percentage gain in flow of 30%
E heads increased volume from 153 to 216 for a percentage enlargement of 41% - not so good for a ratio of 30 to 41!

These numbers show us how port size and velocity is really affected between different heads. And velocity is a direct result of flow vs port volume. Yes, port shape and design will affect this to some extent, but in general, bigger ports slow down velocity as compared to the same amount of flow in smaller ports. And we can assume that the Pontiac engineers had the flow/volume ratio pretty close for the expected RPM range of the stock heads. And they knew enough on the subject to increase both flow and size for the expected higher RPM engines’ operation. Yes, porting quality makes some differences, but when I make these kinds of discussions. I try to assume that all parts being discussed are somewhat similar in quality.

So in summary Skip, quit inferring that I claim that big ports hurt power, and that small ports are superior. Instead, refer to this post for what I have tried to explain to folks for years and have proven clearly with the actual installation and operation of the heads we have discussed.

And Cliff, thanks for the facts about your experiences.

Jim Hand

[JSchmitz]

Originally Posted by Jim Hand

Skip,
Unfortunately you have continually attempted to make any discussion about port volume either black or white - that it either helps or hurts!

Jim Hand

Jim, I will have to respectfully argue that you have tried to make it black and white as much as anyone. I'm not discounting what you have said and believe. I think sometimes we get a little too defensive about our respective opinions.

[Larry Navarro]

I think all of us can agree that, ON THE STREET...smaller port, high velocity is optimal for the lower operating RPM's we use on the street.

Its great that we have the option to go BIGGER ports, like the E-heads, TIGER, etc., if you need the power at the higher RPM's. We know the large port heads lend themselves to that level.

[Tom Vaught]

Quote:

"Since I lack critical tuning knowledge on the DEMON/HOLLEY carbs, I have removed the carb and sent it to "Shaker455" to give it a look and see what he can do to optimize it for my combination."

Boy, that was a mistake! Just kidding Shaker 455 will get you straightened out on the carb I am sure. All you had to do is ask Larry and I am sure that Cliff and I could have helped you too.

Tom V.

[Larry Navarro]

Originally Posted by Tom Vaught

Quote:
All you had to do is ask Larry and I am sure that Cliff and I could have helped you too.

Tom V.

Gee Tom....after all the Barry Grant bashing, I was afraid to ask you.

No really.....

Jeff,(shaker455) has offered before to check out the carb, plus he's a WFO customer.

[Tom Vaught]

Now that I am trying to get BG to offer a Pontiac Tri-Power for everyone I have to be more polite, Larry! I am sure Jeff will fix you up.

Tom V.

[JSchmitz]

Originally Posted by Larry Navarro

I think all of us can agree that, ON THE STREET...smaller port, high velocity is optimal for the lower operating RPM's we use on the street.

Its great that we have the option to go BIGGER ports, like the E-heads, TIGER, etc., if you need the power at the higher RPM's. We know the large port heads lend themselves to that level.

Good summary Larry. I think in some cases we are splitting hairs. Most of us don't have the time or money to go out and test several different, but similar, volume heads. I wish I had the money to test any! I thank all of you who share your information. So that guys like me can make better decisions when we do come up with the cash. I've finally taken some of my time and money to make my car stop and corner better. Instead of always trying to make it accelerate quicker.

[P@blo]

Pontiac engineers knew exactly what they were doing when they designed "small volume" ports to get our big cars moving. Were the round port heads any faster than the D-ports of the same years ?

[Skip Fix]

"Jim, I will have to respectfully argue that you have tried to make it black and white as much as anyone. I'm not discounting what you have said and believe. I think sometimes we get a little too defensive about our respective opinions. "

Not just me Jim.

"I left them on while I did a little more work on the 6X heads that were on temporarily after one of the 64's developed a water leak after 6 years service. Since my engine recognized the added airflow of the KRE heads, I added flow to the 6X's. Since it lost so much low and mid range power due obviously to the 186.5 cc port volume "

I think that statement is definitely implying the large port volume is a problem.

Jim you can re read all of my posts-every time I said that a smaller port with the same cfm will be more effecient if there are no other variables in the head design.Those variables in the head and engine combination are what I am pointing out as opposed to strictly port size. More quality airflowand fuel mixture is the ideal for every combination for what it needs. I think we agree on more things than we disagree. "You say tomatoe, I say tomaato"!

I have always praised your combination for how well it runs, it only does so because of all the attention to detail and parts swapping you have done to keep in in your parameters.And especially the detail in the heads and intake side. I've never said others could not do the same, just that its hard and that added airflow of better heads over perfectly matched heads may get others closer that don't have the tuning skills or time you do. Cliff's single swap of heads and going faster give us a documented example(not saying you can't tune as good as Jim Cliff, just the head change did what I said they could.Jim even you said his increase in power was from better airflow over his previous heads.My MAIN point for years of even using the round port heads before E heads came out.Most of us can't make 2500 passes with the same combination dialing it in.

Yes Pablo look at the mojority of the faster Pontiacs pre E head round ports more than D ports, especially the RAIVs. Dave Schloe running a 10.70 in stock 15 years ago woth RAIVs. Look what the Angeles just ran in Super Stock posted in the race section. Every stock round port has flowed well over every stock D port I've flowed.

You've brought up Floyd's car as another example yourself of a car similar to yours.Jim I was at a PSN shootout when Floyd's car could barely get into the 11s had to use a Holley to do it, not as consistant as yours.(And yes my car did have a problem also there as I threw together a mismatched combination E heads and HO intake, poor convertor just to make the race) I think Floyd has so many of your modifications any other person would also call it a "similar combination" if they were parked side by side.Ported D ports, same cam(now changed) same intake, same cowl air cleaner, same exhaust system, modified Q jet, same modified intake. A body vehicles, Continetal convertor, I'll bet similar gear ratios. Shoot Jim, Floyd and I both have 455s no strokers,the same cam, similar 3" exhaust, same convertor just different top ends,probably similar weights I think many would say he and I have similar combinations. Anyone with an E head 455 could also be considered similar to mine and it wouldn't bother me.

"So a simple statement that since Cliff ran better with the new larger port heads, that alone proves that larger ports don’t affect power, is an incomplete and misleading approach. Also, the fact that less low RPM power might improve traction and therefore is somehow “better” is also misleading. We are talking about power production, and not chassis or tire setups. If there is less power, it is caused by something in the engine!"

That was never my contention, just that more airflow is the bigger factor for improvement secondary to velocity as the most important factor. My main soap box, more airflow can cushion the need for the perfect combination.

You made the statement Cliff lost low end due to the larger heads. His actual numbers show it did not. I was going off your statement.And yes many racers use techniques to kill a little bottom end to hook up and go faster-isn't that what we do at the track, want to go faster. That's why Ken, Ray and many others use staged N2O systems to not use all the HP on the bottom end to hook up, some retard timing so many different ways to help hook up.

Larry I told you just weld an O2 bung in and we can use the AFR to tune that carb, bleeds, jets, PV! got my downleg 850 you can put on now also, for mine the bleeds are way off. A few passes up and down 99 the Grand Parkway and we can get it alot closer.You can ride in mine and see how sluggish my 220 cc heads are at low end too.

[P@blo]

Thanks for responding to my question Skip.

[Jim Hand]

Skip,
I concur that we are in agreement on many aspects of port volume and its affect on power. I would like to summarize some of our statements:

I stated this:
“Since my engine recognized the added airflow of the KRE heads, I added flow to the 6X's. Since it lost so much low and mid range power due obviously to the 186.5 cc port volume "”

And you responded to that statement with this:
“I think that statement is definitely implying the large port volume is a problem.”

Skip, you are absolutely correct – I was indeed implying that too much port volume could be a problem! In fact, that is the crux of all the material I have posted on this thread!

You stated:

“Jim you can re read all of my posts-every time I said that a smaller port with the same cfm will be more efficient if there are no other variables in the head design.”

While I didn’t see that in “all” your posts, I agree with your statement completely.

You mentioned my experience at the drag strip:

“Most of us can't make 2500 passes with the same combination dialing it in.”

Skip, I agree completely. However that is how I have made my car run respectable, and have learned most of the material I am trying to pass on to the readers via topics like this one.

I posted this;

“So a simple statement that since Cliff ran better with the new larger port heads, that alone proves that larger ports don’t affect power, is an incomplete and misleading approach.”

You responded with this statement:

“That was never my contention, just that more airflow is the bigger factor for improvement secondary to velocity as the most important factor.”

Skip, I agree with that, and was very glad to see you finally make that statement since previous posts you made implied the opposite.

All the discussions about Cliff’s car were really not applicable to what I discussed about my car. His car is considerably lighter, has a higher converter flash stall point, and is developing considerably less power then my engine (although that may change with his recent additions of cam and intake). Cliff also installed superior MT ET Radial rear tires almost concurrently with the change of heads because his old ones were worn out. And I see discussion about his car only as a diversion from the fact that I have proven that port volume is important and excessive volume does indeed cost power when not correctly matched to the application. And not only have I proven and stated it many times, but a host of other technical resources confirm the same thing.

In the fun and excitement of exchanging such information, and trying to clarify certain points, I may have included unneeded personal comments. I regret that, and if they seemed uncalled for, I apologize for any and all such comments.

This had indeed been a fun and informative thread. I appreciate the civility of all involved.

Jim Hand

[Skip Fix]

Pablo another way to look at factory roundport vs D ports are factory HP ratings and NHRA hp ratings, and as related to this discussion their intake port ccs. These are factory ratings with Pontiac engineering, I assume they were not shooting for loss of bottom end or overall performance but look at the ccs Pontiac engineers used. The head cc for a round port intake averages 185cc-pretty close to the ccs of higher flowing KRE D port!

Factory HP (using McCarthy's book as a reference)-IE untouched heads:
1969 RA IV 10 hp over RAIII dports,722 port cc intake/ex 187/162, 16 156/142cc
70 A body RAIV 4 hp over RAIII, F body 25 hp over RAIII
1971 455 HO 10 hp over D port A&F body
1972 455 HO 50 hp over other available 455s
1973 455 SD 40 hp over D port 455
1974 SD 40 hp over D port 455 -SD port cc 188 intake/182 ex, 4X 156/142

I can't seem to pull up the current NHRA hp factors from their web site but they have generally been higher than the equivalent D port that same year by more than 10 hp. NHRA watches actual track times with different combinations (weight/factored hp) and

You can see the big difference in port sizes the factory used. I would assume their engineers knew how port volume might affect performance.

Jim I know you don't have as much personal experience with round ports as D ports but a few paragraphs to mention them in your book might be a good addition for future editions to complete the history of high performance Pontiacs as you did in the intake section.In 72 if you wanted a 455 F body it had to be a round port.You mentioned the KREs-I'll bet there are alot more round port iron heads around than KREs. Rocky Rotella has had some good air flow data on some of the different intakes also including a 73-74 SD that maybe could be included also.

[Skip Fix]

Jim we were posting again at the same time. In any "research team", and I feel our Pontiac community is a team against the "other guys" that look down on us, different people seem different things from the same data. My dad's and uncles are engineers, I've got a science degree and looking at data from all sides and questioning it is how we develop new drugs, new products. In my field now study funding must be disclosed to look at a potential direction the data interpretation slant. That isn't a bad thing and doesn't have to be a personal thing.You and I have always had different slants to get to the same goal -a fast Pontiac.

I did take this one comment personally, I can't speak for Cliff.

"How would he or you possibly know what effect the various parameters of airflow, port volume, velocity, etc., had on the change?"

I've achieved my interpretation and slant on Pontiacs from reading, observation of combinations,flow testing and dyno testing,track times with different parts and settings as you have , just maybe a lot fewer years and passes. I've tried some off the wall ideas that have helped my combinations also(more intake duration, 1.8 rockers), but might not others.

My slant-more added airflow even if a little more than optimum can make up for the the loss of velocity of a smaller more effecient port and give us poorer tuners the ability to run faster with less tuning.Our piston speed of our motors especially a 455+ wil overcome the slower velocity of even a 215cc port and stil make more hp. Yours has always been using just the optimal flow is all you need because it works for you and your combination(where your attention to detail, track tuning times,ability to feel 0.1 second comes in the equation). That's something that comes easy for you but not everyone.

My main data point was when I started with the bigger cc RAIV heads. That was my first high performance Pontiac motor. My machinist was one who here in Houston had one of the first flow benches and dynos. He raced Pontiacs (and Mopars Tom) in NHRA stock classes. He cleaned up my heads, I had a 455 block we were to use them on, to kill some compression we cut the pistons for a .100 down deck(bad idea for quench but still worked good,might have been better) UD 231/239 cam, HO intake, Q jet. When we dynoed it through mufflers we couldn't really get a definitive torque peak as it had som much bottoom end compared to even high HP BBC he'd dynoed. Somewhere on his conservative dyno of 480 ftlbs around 2800. 430 hp at 6000. Pushed my car with road race suspension A/c , 3.42 gears weighing 3950 to 12.30s @ 117 open headers on 16" diameter DOTs that were available in 1991. After being impressed with my motor for another customer he built another 455, ported 6x heads on his flow bench, HO intake, same exact cam degreed the same , better deck and was 80 hp off mine as even the ported 6Xs didn't have the same airflow. Those same heads on a 400 ran 12 teens @ 111 through mufflers in the heat weighing 3900lbs, something I haven't seen to many 400 do, but others have.

After one of the PSN lectures you had a local friend went to try and duplicate your 64 head 455 combination. Pocket ported by him D ports same chamber size-I flowed and were decent flowing. Same Wolverine cam, degreed the same, cast iron intake, Q jet,headers HEI-what I consider pretty similar motor .It was barely in the 13s because he couldn't/wouldn't take the time to tune it in like you did. So not as easy to do. I think many others do the same and are disappointed in the results because they also can't dial it in like you have. From actually looking at and flowing many sets of ported D ports from some of the big names I will guarantee the CCs are going to be closer to Larry's 180 than your smaller ones you took more time and effort on. That's also what the general public has to use when they look to more airflow in a Dport.

Another my first E-head motor, once I got a good drivetrain and closer matched components clicks off 11 teens in heat and 10.90s @ 123 mph in good air staying in my preference parameters -factory Shaker scoop and base,power brakes, 9" slicks, mufflers and tailpipes-rpm not a specific parameter. Maybe only 30 passes of tuning. My current pump gas motor poor track a spinning 11.30s @ 122 mph same parameters with only 3 passes. Something I don't think I could do with D ports.

Steve Coombs combination jumped signifigantly with E heads over his well ported D ports.

I think Cliff's results speaks to my same slant-more airflow even with a bigger port can make good hp with minimal if any fall of bottom end loss.Would an even higher velocity same cfm head have made more-probably so, but that test wasn't done.

My "intepretation" of the KREs on your combination are the increased cc are probably the main factor in the bottom end loss but we have the added variables(more than just one change the ccs) of aluminum vs iron with different compression ratios, different valve seat angles than Cliff's heads, possibly a different intake/exhaust ratio that used the same cam.

I have never discounted how fast your car can go with smaller ports, and factory components, just that I and many others couldn't duplicate it and need the crutch of a little extra airflow. Both can get you a fast Pontiac and neither are wrong approaches. Shoot Tom S has a great time with dual quads and RAV HUGE ports on the street.

[Larry Navarro]

TTT

[blaktopr]

New to this forum, and a nobody in the Pontiac community, I would like to chime in, right or wrong.
Street forum...........port volume vs. cfm. For what I have gathered over the years through hands on, testing, mistakes and reading, Like Jim is trying to point out, best airflow to size of port. A question of "can you be too small", I feel yes.....but based on the size of motor and intended RPM range. As Jim points out and tries to show is that for a street 455-472 from 5500-5700 those cc runners work very well. For the "why not me?" question, or "why is he faster?".....my heads flow 260 or mine flow 280 (sure....) is who did the heads.
10 heads all ported to 250 cfm....all 10 heads may all perform differently. For what I am finding out is that where the material was taken and how the cross sections of the port are worked to provide a runner useful for the intended rpm range the particular size motor is running. One cam profile will work with 2 heads, another with 3, and 1 and so on.
Even with the aluminum heads. CNC PORTING!!!......but....to which engine combo???????? Whos head is better for a street car, 310 or 320 cfm? Whats your street car, the 5500rpm 455 or a 6500rpm 462? If you want to stay at 5000-6000rpm, I feel, listen to what Jim has to say. If you want to go more cfm and aluminum heads with a larger csa, then try to get the motor to run the rpm that head is capable of feeding for best VE.
I personally hate seeing E-heads on cars with small rollers shifting at 5800 and running the same as a d port car. Or the large roller in a stroker motor and shifting at 6000, e-heads and a low 11 or high 10 second timeslip. Rev that thing!
I am no engine guru, just learned from a pontiac builder in the past and then parted ways. There is more to getting peak performance than bolting parts on.....yeah that old cliche. But it seems that is what some people are doing now with all these parts out now.
I'll stop here. And what is .1 to .3 worth? 14.00-13.99, in the 13's
13.15-12.95, in the 12's
11.80-11.50, oops, need a bar
How about this,
Jetting........ 0.3
Timing.........0.1
taking 1 battery out .04., yes .04
Then to come back with slightly better conditions... .03
Running 9.98 with a 400.............priceless!

[J.C.you]

[QUOTE=Steve C.]

But what I really do miss is the feel of power winding it up to 6000 rpm....

this lower rpm weezing out and going around shifting at only 5500 rpm's......
--------------------------------------------------------------------------

i believe you are on to something in this discussion........ maybe a bigger port likes some more Rs.......among other things......maybe more stall, bigger headers, cam, gearing, and the list goes on, hummnnnnn.....

engine masters is a great example, as Kaase's engine looked to have a smallish port volume, although over 500cubes. BUT they were only spinning to 6500rpm....... increase the usable rpm range and port volumes will increase..... as the engine will want more air......... only get so much NA air thru a certain size/shaped hole......

[Region Warrior]

Since Rays name came up, at the risk of getting in trouble...
After getting back on track, ET's are close to the same as before.
But the car is going a few mph slower. It "feels" like it's running out of power before the end of the 1/4.
We are not sure why. Made to many changes at one time. Cam, gearing, etc.
Since the engine is down for freshening, he decided to have the heads flowed by a friend to verify the flow #'s.
That way we can try a different profile cam if needed.
I tagged along with one of my e-heads to compare.
I dont remember exact #'s. It was a few weeks ago, so dont quote me. Sheets were being mailed to Ray.
His CNC wide ports flowed either 340 or 360cfm.
My hand ported (non wide ports) flowed 305-310cfm.
Valves on both heads are 2.19
What got my attention is mine flow more air with less turbulence up to 600.
The wide ports go further of course, but at a slower velocity.
I think with the right bore and stroke (under 500ci turning less rpm's) i could give him a run for his money.