[Cliff R]

We finally finished up late yesterday with our dyno testing at KRE. For those that haven't been following the testing, we pulled our flawlessly running 455 engine topped with KRE's aluminum 85cc "D" port heads to repair an oil leak at the back of the pan. We freshened up the engine and decided to do a cam swap. The old Crower 60919 (RAIV clone) cam was replaced with a Comp Cam's custom 240/248/112 flat solid grind using their latest XTQ lobes. It made less power than the old cam, so it was replaced with a custom hydraulic roller cam, also from Comp Cams.

The HR cam has similiar .050" numbers and lobe placement as the Crower cam, but that's where the similiarity ends. It sports much greater .200" numbers and a lot more total valve lift.

We started testing with a known intake/carb combination supplied by KRE, a T-II intake/HP 950 Holley, to get some baseline numbers. We spent most of the first day chasing down a few problems, changed plugs, wires and even the distributor to find a high speed miss, only to discover that the rocker arms were smacking the valve covers do the increased lobe lift from the new cam! We basically wasted a half dozen pulls, but made some pretty good power on the final pull the first day, 509HP/551TQ.

We started the second day of testing with the iron intake/Qjet and made 504HP and 559TQ. The dual plane intake fattened up the torque numbers across the 3500-4500rpm range and were a solid improvment over the best numbers we ran a over a year ago when the heads were first installed on the engine. The best pull we made then was 494HP/550TQ.

The vacuum numbers up near the top of the pulls were slightly higher than our first testing. We installed our RPM intake and low and behold the power numbers jumped to 514HP/574TQ.

We finished up the testing running a couple of different carburetors. The Holley HP was tested against our Q-jet, and just like a year ago for the first testing it made just a tad less peak power, 512HP/570TQ, but within 1HP/1ftlb AVERAGE power. The power curve is just a tad smoother with the Holley carb, even though it makes a bit less power.

Overall, our new modifications were a great success. We didn't make any mind boggling improvments simply by looking at the numbers, but we did make improvments to power production at every rpm within the range we run the engine. Idle quality with the new HR roller cam is excellent, 13.5" of vacuum at 750rpm's, about equal to our old cam with the Rhoad's lifters.

Directly comparing the PEAK power numbers from our original combo are as follows: Crower cam/iron intake/Q-jet....494HP/550TQ, HR cam/iron intake/Q-jet....504HP/559TQ, HR cam/RPM intake/Q-jet.....514HP/574TQ.

Directly comparing AVERAGE power numbers from our original combo are as follows: Crower cam/iron intake/Q-jet....452.5HP/525.3TQ, HR cam/iron intake/Q-jet.....454.4HP/527.9TQ, HR cam/RPM intake/Q-jet....468.8HP/544.4TQ.

Those are the basic numbers from the testing. There is a LOT more that goes on behind the scenes to get to these numbers. Timing/jetting changes, rocker arm ratio's, etc. My hat is off to the guys at Kauffman Racing Equipment, for the time and effort put into the project, we all certainly learned quite a bit over the past couple of weeks.

I'm sure the results will generate some questions, we'll try to answer them as accurately as possible, but keep in mind that we will not release the HR cam specifications. Also bear in mind that we pulled the engine from 3500-5700rpm for all testing. We were already making peak torque at the onset of the pulls and no doubt our combination enjoys around 550tq down as low as 3000rpm's where the converter stalls. Even so, dyno's are not incredibly effective at holding that kind of power at low rpm's without running out of brake toward the end of the pulls. This mandates starting the pulls a bit higher in the rpm range so we can see what kind of peak HP is being produced. Even doing so, just like a year ago, the dyno still had minor troubles holding the engine up near the end of the pulls. We're not really concerned with power production that high in the rpm range, so it really isn't a problem for our testing.

I would also note that we have already ran an RPM intake with our old combination, as we built and tested the first 455 engine for KRE that used their new aluminum "D" port 85cc heads, Crower 60919 cam, etc. It made almost identical power as our iron intake did topped with an RPM intake, about 492HP/550TQ....and...that particular engine used a much lighter piston, 6.8" rods and low drag ring pack. I didn't want anyone to get the impression that the RPM intake had a MAJOR impact in the total power improvements all by itself. We keep finding out every time we go to the dyno that it's all about the COMBINATION of parts, not one part in particular, that yield the best overall results!......Cliff

[TCSGTO]

Great info Cliff!! It looks like the HR cam should beat the RAIV clone by around .2 in ET.
At what RPM did HP peak with the HR? Was there a sharp drop once the peak was reached?
Again, great job in setting up a fair comparison of like duration cams.

[gearbanger]

Cliff,

I was looking at the numbers and I expected to see the average power numbers to be quite a bit higher on the HR than the flat cam, but they appear to be only about 2hp and 2ft/lb more. That puzzles me. Why do you think that is and in my mind I would say that would not be worth the change to the roller. What do you think?

It seems like that RPM intake is the trick. I have one on my car and I am very glad to see that. My HR is 242/250 on 112, What is the one you used?

I really appreciate you soing this Cliff. This is huge for guys building Pontiacs!

[TCSGTO]

[QUOTE=gearbanger]Cliff,

I was looking at the numbers and I expected to see the average power numbers to be quite a bit higher on the HR than the flat cam, but they appear to be only about 2hp and 2ft/lb more. QUOTE]

It just goes to show Cliff had this combo pretty well scienced out already and changing one part of the equation wasn't going to make a radical difference.

[P@blo]

There was an small improvement in average power #'s with the stock intake and the HR showed a big improvement over the HFT when a RPM was used. I was looking at Comp Cams web site and the dynos they post tell a similar story with small improvements in the power band. But they tested with a performer intake and may have shown better numbers with the use of the RPM manifold and better heads. So the AVERAGE power # improvements seen on the dyno are:

Factory Intake : +1.9HP +2.6#'s Torque
RPM Intake : +16.3HP +19.1#'s Torque



Thanks for sharing your results with all of us Cliff.

[Ron H]

Thanks Cliff. I hope you are happy with the HR findings. I am curious to know if you think it is worth swapping to the HR cam due to cost. You said you had more torque etc, this should get ypou out of the hole better. What kind of improvement would you expect on 1/4 mile times?

[gearbanger]

Okay, after reading that post again, it seems like with the HR cam, the iron intake was holding it back some. Then with the RPM it allowed some more power to be produced.

So basically it looks like the stock intake can get you to 500 hp. Sounds reminesent of Jim Hand articles doesn't it

I am also wondering what exhaust you have? Are you using headers or HO manifolds or what?

[Cliff R]

First and foremost, the HR cam was chosen to provide similiar power to the old cam, just more of it all all points. It easily accomplished that, with no other changes. It is not a copy of, or anything really that close to the old .470" lift flat tappet grind. The lobe profiles and lift are much more generous. The ONLY similiarities between the cams are the .050" numbers. Changing the cam alone only accounted for some additional power increase at every rpm, unlike the flat solid which lost power across the rpm range. We considered the back to back testing successful. With the new cam in place, it provides the airflow potential to make much more power, as we saw when the RPM intake was installed. This shows us that we were pretty much "optimized" with the old combination of parts, and a cam change alone WAS NOT going to make any dramatic improvments to it.

My opinion, the factory 041 cam and it's clones are very good parts for this particular application, as is the factory dual plane iron intake. Making more power within this particular RPM range is going to be a difficult undertaking, as we quickly found out during the past couple of weeks.

What we were able to do, is choose a cam that gave up NOTHING at idle and low speeds, yet delivered more power across the rpm range. Then, when we opened up the intake to delivery more air, the power numbers took big jump.

As far as cost vs power increase, that would be completely up to the individule who's paying for the parts, and the intended goal(s) for their particular project? We're talking about spending about $250 for a flat hydraulic cam/Rhoad's lifters, $300 for a custom flat solid with real Pontiac lifters, or close to $900 for the hydraulic roller set-up. For our set-up, each application also required a custom set of pushrods, about $125.

The roller cams also take "scrubbing" a lobe out of the equation, and take some friction/heat out of the assembly. Cam changes now simply become a matter of changing the cam, no worries about break-in, lifter/lobe failure, etc. There is also some contraversy about using HR cams with higher rpm engines as the weight of the tappets come into play at some point? I'm been assured by KRE, Dave and SD Performance and several others that the HR cams/lifters currently being offered are fine to at least 5800rpm's, and even higher with lighter retainers/valve train parts.

A couple of more ft/lbs and HP improvement at all points really doesn't seem like much at a glance. Since we run a wide rpm range at the track, it will improve ET/MPH, we woln't find out exactly how much for several months. Just running the basic numbers, probably a couple of tenths and 1-2 mph.......Cliff

[David Jones]

A couple of more ft/lbs and HP improvement at all points really doesn't seem like much at a glance. Since we run a wide rpm range at the track, it will improve ET/MPH, we woln't find out exactly how much for several months. Just running the basic numbers, probably a couple of tenths and 1-2 mph.......Cliff

......in an engine that idles as good or better than before. That generally doesn't work that way.

[Cliff R]

Okay, after reading that post again, it seems like with the HR cam, the iron intake was holding it back some. Then with the RPM it allowed some more power to be produced.

No doubt about it, we DID NOT see any numbers close to those we made yesterday, running the RPM intake with the old combination. Actually, our iron intake (modified) made near identical power to the RPM intake during previous testing. The HR cam, obviously brings a lot more potential to the combination.....Cliff

[kyle_blake]

I always enjoy reading your posts Cliff.
Thanks.

[BruceWilkie]

This is good info! So next year when you have gotten all you can out of this combo is it time to see what a ported set of KRE's might do? Perhaps some massaging of the RPM intake? Some exhaust tuning? The never ending evolution goes on!

[Skip Fix]

Great info Cliff. I've been pondering HRs for awhile. Be good to see what your 850 does as the HP 950 has smaller venturis than it, basically a 750 body with 850 throttle blades, since it seems to like the extra airflow.

Did you all stop at 5700 because the HP/TQ was falling off , or just the rpm range you were to run in? My recent KRE E head 455 with a slightly larger flat tappet hydraulic(239/247 @ 0.050) had a HP peak at 6200, so slight bigger heads and a little more cam, so could be the reason for the increased rpm HP peak.

[tommieboy]

Originally Posted by Cliff R

.....but keep in mind that we will not release the HR cam specifications.

Ever???

[Cliff R]

Skip, the dyno brake was "letting go" around 5400-5500rpm's as it was. We wanted to get a good idea of the total power production (torque) in the rpm range we run in. I don't rev this engine past 5000rpm's for most racing that we do, so the most important power occurs between about 3200rpm and about 5200rpm. These engines make so much power down around 3000-3500rpm that the dyno brake has to be adjusted to hold them. Doing this at such a low rpm makes it difficult to keep it from releasing at higher rpm's. I'm no dyno "whiz", but Jeff Kauffman had to make a few minor adjustments to the brake to get it to work correctly.

The power curves flattened right back out when we switched from the flat solid to the HR cam. Torque production is near a flat curve from the start of the pulls out to about 4400rpm's, where it gradually starts falling off. We're seeing 570's torque at the onset of the pulls and still making over 500 ft lbs out to 5400rpm's. HP curves flatten out up around 4800rpm's and stay right there to at least 5400rpm's.

Kauffman Racing Equipment spends a lot of time/funds coming up with their combinations. We used a custom grind selected by them, I'll leave it up to them if/when they want to release the specifications? I will say that they have ran this cam before, and a slightly larger version, which actually gave up a slight amount of power!......Cliff

[77TA]

Originally Posted by tommieboy

Ever???

I can resepct that they want to guard the specs. I kinda got sworn to the same when I purchsed my last new cam. Some may not understand that.

[P@blo]

Cliff, will the HR be the cam you stay with or do you think you might ever go back to a HFT ?. Thanks again for sharing your test results.

[Tom Vaught]

Has the Kauffmans actually ever "scaled" their dyno with a calibrated weight on a calibration beam?

Tom V.

[gearbanger]

Cliff,

Do you think your heads are now the limiting factor for more power? At 260 cfm, you are probably getting close to NA power potential at 514 hp. I wonder if the larger cam gave up power because of the heads not flowing what the cam wanted?

I have a custom KRE hyd roller that is a step bigger than the one you have, and I have been really impressed by the power but I have no dyno runs to back it up. The heads I have are the 310 versions of the aluminum D's. My cam definitely has a mean sounding idle and I'm sure it is not as peppy right off idle as your setup.

[slowbird]

A couple of things. It appears that the RPM intake out power the T2 intake. And the cast intake was about equal to the T2 intake.

Also it would be interesting to see what would happen it you had put 1.8 rockers on the Crower cam. Skip Fix seems to be running very well with his hyd cam and 1.8 rockers.