[TransAm 474]

I am in the planning stages of upgrading my 461. It currently is a typical 400 Stroker build, 4.25 stroke, 6.7 H-Beam rods, and Ross Flat Tops. It has SD Performance 6X-8 street 245cfm heads, 9.1 compression with piston .005" in the hole and 1016 .039" gaskets. I'm running the Rollmaster Billet timing set, Romac Damper, Performer RPM intake, and Quick Fuel 750. The current camshaft is an old custom Ultradyne Solid Flat Tappet, 288/301 Adv Duration, 255/268@.050", .540"/.552" lift w/1.5 Harland Sharp rockers, 106* intake Centerline, 112* lobe seperation. The exhaust is 1 3/4" Hedman headers, and dual 3" R.A.R.E. exhaust, Dr. Gas X-pipe, 3" Dynomax UltraFlo 17229 mufflers with Pypes 3" tailpipes. Transmission is a TH400 with custom TCS 11" 2800-3000 stall converter from SD Performance and 3.73 gears. It is a 1978 Trans Am, 100% Street car running pump gas. Not sure what the current setup puts out, maybe 450hp/525tq or so?

Here are the upgrades I want to do... my goal is to make 600hp/600+tq on pump gas, and still retain decent street manners, although it will not be daily driven, but is a street car.

I actually have been talking to KRE a bit, and they recommended their 325cfm D-Port along with the matching Northwind intake to me for my current solid camshaft to meet my goal. I'm debating whether or not to change the camshaft to a Hyd Roller, or stick with my current solid flat tappet camshaft. I mentioned it too KRE, but he thought my current camshaft looked pretty decent, but I also told him I was gonna stick with it at that time. Whatever camshaft I choose will have 1.65 rockers.

Now, I'm also gonna switch the Quick Fuel carb to the Fitech EFI for better Cold starts, Throttle Response, and driveability.

I have a couple different choices on compression, I would naturally like as much as I can get by with, and I know that depends on camshaft choice as well. I know Cliff runs 11.0-1 or more on pump gas. If I buy the heads with an 85cc chamber, my piston is in the hole .005", and using 6.6cc for the valve reliefs in my Ross Pistons, using a .030" gasket would give me an excellent .035" quench, and compression would be exaclty 10.5-1. If I buy the 74cc head, it would have too much compression, at 11.68-1, although I could lower it with a thicker head gasket, that's not ideal as I would lose my excellent quench. If I can get the heads with a 80cc chamber, I can retain the excellent .035 quench, and come out with exactly 11.0-1 compression, that's kind of what I was shooting for, since Cliff has been sucessful with it, but I also want to be sure I don't have any problem with running premium 91 octane pump gas.

So, I haven't decided what to do about the camshaft just yet. I'm not sure the $1000+ to change to a Hyd Roller would be worth it over my current camshaft. Just to give an idea of what I'm looking at, if I decide too, here are some custom lobe number I was looking at. All of these are Comp Cams XFI Hyd Roller lobes. Which would you choose for this particular build, if you were building it?

Camshaft #1)

Intake Lobe 3018B.... 286 Adv. / 236@.050 / 159@.200 / .363" Lobe lift

Exhaust Lobe 3038B.... 294 Adv / 242@.050 / 163@.200 / .360" Lobe lift

112*LS+4 (108 I.C.)

Camshaft #2)

Intake Lobe 13084.... 290 Adv / 240@.050 / 163@.200 / .364" Lobe Lift

Exhaust Lobe 13144.. 298 Adv / 246@.050 / 167@.200 / .361" Lobe lift

112*LS+4 (108 I.C.)

Camshaft #3)

Intake Lobe 13085.... 294 Adv / 244@.050 / 166@.200 / .366" Lobe lift

Exhaust Lobe 13145... 302 Adv / 250@.050 / 171@.200 / .363" Lobe lift

114*LS+4 (110 I.C.)

Camshaft #4) Current Ultradyne Solid Flat Tappet

Intake Lobe .... 288 Adv / 255@.050 / Not Sure@.200 / .360" Lobe lift

Exhaust Lobe.. 301 Adv / 268@.050 / Not Sure@.200 / .367" Lobe lift

112* LS / 106* I.C.

Now, Camshaft 1, 2 and 3 are just lobes that I chose for no particular reason, I just thought they may work decent, they are all Comps XFI Lobes. Feel free to recommend others as well, if you think something would work better.

Just to recap....

Combination

1978 Trans Am Street car

461 Stroker
KRE 325cfm D-Ports
Northwind Intake
Fitech 1200PA EFI 30012
Either 10.5-1 or 11.0-1 Compression
.035" Quench
1 3/4 Hedman headers
Dual 3" exhaust with X-pipe and UltraFlo muffler's and 3" tailpipes
TH400 Transmission
11" TCS 2800-3000 stall converter
3.73 gears

Goal- 600+hp/ 600+tq
Premium pump gas 91 octane
Street car (not daily driven)
As you can see from my current camshaft, I can tolerate a pretty hefty camshaft on the street. I can change the converter and gears accordingly, if I need too. I will run Harland Sharp 1.65 rockers on whichever camshaft I go with.

What camshaft and compression would you go with, and why? Thanks!

[steve25]

So your able with the car set up as it is now to fully hook up the power it's making with its current Cam?

[TransAm 474]

Not completley, currently, but the suspension is getting updated as well, and will be running Drag Radials.

[steve25]

As you where already informed the Cam you have now is good to achieve very close to your goal, but you need more Cylinder head flow!
You could get your 6X heads reported to a 275 cfm @28" level, or go with even just a 300 cfm aftermarket D port as that will be enough.

[Formulajones]

11:1 with an aluminum head is actually not that difficult to run on pump gas. I'm doing it with a set of iron heads on one engine.

I'm aware of several 11:1 aluminum head setups that run great on pump gas. Dad is running 10.84:1 on 91 octane here in the AZ summer heat, it's been perfectly fine.

I like your idea of the 10.5:1 setup with tight quench. That's plenty to reach your HP goal without pushing the compression envelope. I run another aluminum headed engine here at 10.2:1 that makes your HP goal, with a mild hydraulic roller, and that thing runs on 87 if I desire, and never complains.

[Steve C.]

Here are the UltraDyne lobes:

http://www.bulletcams.com/Masters/ultradynemasters.html

Your intake lobe #F1 is listed with 166 degrees at 0.200" lift.

Lobe #F19 is similar to your exhaust lobe.


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[pastry_chef]

What size exhaust valve and ballpark CFM?

[TransAm 474]

Thanks for the great advice, and thanks for listing the Ultradyne lobes Steve. My current solid cam lobes are indeed the F1 Intake lobe, and F19 Exhaust lobe. So it has

Intake Lobe F1... 288 Adv / 255@.050 / 166@.200 / .360" Lobe lift

Exhaust Lobe F19... 301 Adv / 267@.050 / 176@.200 / .3677" Lobe Lift

112* Lobe Seperation / 106* I.C.

So, judging by the duration at .200 numbers, the rollers I listed actually doesnt look as good to me, as what I already have, so it seems that my current camshaft is pretty decent for this build, and should make my goal fairly easy. It runs with about 8" of vacuum at idle currently, but that only with 9.1-1 conpression, so idle, and vacuum should improve with the new build having 10.5-11.0-1 compression, correct?

I also see alot of the success by Cliff and others running so much compression on Pump Gas, contributed to installing the camshaft at 109-110 I.C., mine stated 106 on the card when I installed it, would I benifit from moving mine too 109-110 as well?

At this point, it looks like it would be best to stay with my current camshaft, and put the $1000+ that it would cost to change over to roller, towards the rest of the upgrades. What do you think?

[Steve C.]

Stated- " So, judging by the duration at .200 numbers, the rollers I listed actually doesn't look as good to me, as what I already have...."

Let's look at one of the lobes you listed for conversation.

Intake Lobe 13085.... 294 Adv / 244@.050 / 166@.200 / .366" Lobe lift

Your current intake lobe has in theory 0.522" net valve lift. This based on a assumed true 1.5 ratio and 0.018" lash. The hydraulic intake lobe you mention above has in theory 0.549" lift. This is positive as a 2-valve engine responds to high lift. David Vizard has stated, "If you want to build a street motor with the most power without a sacrifice of idle and low speed qualities, then lift is the most important factor to maximize, not duration".

Now note both have the same 166 degrees duration at 0.200" lift.

Your current cam does have more 0.050" duration but we know that when going from a hydraulic to a solid you must add duration, here it's 11 degrees. There is no set amount to add, some say 8 to 10 degrees but it will vary. But to illustrate this I will point out that that the popular Comp Extreme Energy hydraulic roller lobe 3315 with 230 degrees at .050" tappet lift is similar to the Comp 6055 solid flat tappet lobe that has an additional 6 degrees duration at .050" tappet lift. Yet tested on a Spintron machine with a 1.5 rocker ratio the hyd roller has 240 degrees at .050" tappet lift and the solid flat tappet has 241 degrees at .050" tappet lift. That said, the roller will have more area thru the entire lift curve.

Last you can't compare the advertised duration without noting the solid is rated at 0.020" tappet lift and the hydraulic probably at 0.006" tappet lift, therefore the solid if measured at 0.006" will have more duration than the 288 degrees indicated here. To help illustrate this the Comp solid flat tappet lobe above has 300 degrees duration at 0.0006" tappet lift. It's rated with 274 degrees at .020" tappet lift.

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[gtofreek]

I had this cam ground on a 112 ° LSA, and put it in a 455 with un-ported KRE D-ports, and made 550 HP, and 553 ft. lbs. and still made over 500 HP at 6200 RPM with RA exhaust manifolds. With better heads, you just may meet your goals.

Sorry, I forgot the link.
https://www.lunatipower.com/Product....d=3211&gid=289

[ta man]

I think you need to set a budget and a time frame to meet all your goals. I would seriously think about going to a roller cam and doing the fuel injection at a later time if the roller eats up too much of the budget.
I would also suggest buying the heads and cam from the same supplier, there are many proven "Pontiac" vendors that will properly setup the heads to match the cam to provide a long service life with no issues.
600hp is the old "500hp" its achievable just follow what others have done.

[Skip Fix]

A real 600 is going to be a little stretch unless you have a fairly aggressive cam. My UD HFT 239/247 is making around 550-575 based on mph dynoed only 525 on a conservative dyno. A SFT has to be bigger at 0.050 to compare to a HFT, discussions have not a specific range of increase.

[Cliff R]

Don't look simply at peak HP but look at power (torque) and even more average power.

We already know that the Old Faithful cam with 295cfm KRE heads, 10 to 1 compression, RPM intake, Q-jet, no spacer and a good set of 4 tube headers will make 552hp/604tq with over 500ft lbs clear across the entire loaded rpm range and over 550ft lbs for a good portion of it.

We also know that we can build the same 455 with 10.5 and even 11 to 1 compression and it will make even more power and still fine on pump gas.

In addition we can move up to a large cam like the Road Paver and even though it will put you closer to your 600hp goal it woln't idle as well, or be as user friendly, nor will it make any much more power down where you will use it and need it the most. So yes you can get close to your HP goal, but not without diminishing returns, and the 2800-3000stall 11" converter will certainly not like that move as well.....IMHO.......Cliff

[Steve C.]

"We decided to do some intake manifold comparison testing on a 474ci engine running a set of our 290cfm CNC ported KRE D-port heads with 10.2 to 1 compression on 91 octane fuel with a 236/245 duration hyd. roller cam."

"This concluded the testing with the Q-jet as the next intake the Torker II has a square bore plenum so we installed a 950HP Holley on top of it with a 1" open spacer for the last test. The Torker II didn't disappoint and produced 554hp @ 5500rpm and 584 lb ft @ 4500 rpm."


http://www.sdperformance.com/newsStory.php?newsID=44


.

[Steve C.]

A fellow here on the board uses the 246/252 'Road Paver' hydraulic roller cam with a 112 lobe separation in conjunction with solid roller lifters in a .030-over 455 street car. With a 4.250" stroke, 305 cfm KRE d-port heads, 1.52 ratio rockers, Torker II intake & 950 Holley carb w/ 1-inch spacer. I believe the compression is around 10.5:1

It made 589.7 hp at 5800 rpm and 531 ft. lbs. torque at 4700 rpm.

His statement....

"The converter is a 10" and flashes to around 3000 off the line just with foot braking. It probably stalls around 2k when driving normally.. The engine is very street-able. Makes 12 inch vacuum. The thing is a beast when when you get into it."

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[Steve C.]

My previous 4.210" stroke / 462cid combo made 600.9 hp at 6000 rpm with a lousy 9.7 compression using a Victor intake and 1/2-inch open spacer.

Shown here with a Performer RPM intake:

http://www.pontiacstreetperformance....455sc2003.html

No issues on the street. Never track tested with the Victor intake but ran 10.88 with the RPM intake.


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[TransAm 474]

Thanks for the great advice guys. I know from reading here, the Old Faithful is a proven camshaft in these type of builds. My theory was, since I'm shooting for 11.0-1 compression instead of in the popular 10.3 range, and running a 325cfm head instead of a 295-310 head, that I may be able to use a bit bigger camshaft on a little wider Lobe Seperation, and have close to the same Idle and street manners as the Old Faithful. That is why I included camshaft #3 XFI Lobes above with 294/302 Adv 244/250@.050, but with a 114* lobe seperation, instead of 112 like the rest. But you all sure have alot more experience and knowledge at this than what I do for sure! Lol. As far as the converter goes, I can always change it to whatever I need too. Then after thinking about all that, I just didn't know if it would be worth the expense of changing it over to roller, compared to the gains I would see on the street over my current SFT. I do realize my current SFT is pretty hefty for a street camshaft, but I thought it may improve with the compressing being increased from 9.1 to 11.0-1, but again, this is the reason I need your guidance, because you all are way more knowledge on this stuff. I'm not necessarily looking for the hp to peak "600hp", I was just stating my goal is "600hp/600tq", I would "like" to have that much, but I do indeed want a broad, flat torque curve. I just didn't know how my current camshaft would work vs. the 3 I posted above, or if I would see enough gain to be worth switching to roller, since it is a street motor. Thank You, I appreciate you guys.

[Cliff R]

The Comp XFI lobes are smaller than the Old Faithful and Road Paver lobes, so not really an apples to apples comparison nor will they make as much power with the same approximate duration specs.

The XFI lobes still work very well and I've used quite a few of them, but mostly in the lower compression ratio 455 HO and Super Duty engines.

The Road Paver cam idles a LOT better than one would think it would just by looking at it on paper compared to the slightly smaller Old Faithful grind. Even Dave's even large solid roller cam with specs similar to the Road Paver idles like a kitten in a 325cfm KRE headed 455 build. We did one here using that cam and it will idle right down to 700-750rpms and although it has decent "lope" it's not nearly as "rough" as one would expect it to be.....FWIW......Cliff

[TransAm 474]

Thanks Cliff, are you referring to the 112 or 114 version of the Road Paver? I initially had in mind that the Road Paver camshaft would be a great choice for this build. I also see KRE has a Hyd Roller that is similar in spec to the RP as well. Going by the the specs on paper, how would the manners of the RP compare to my current camshaft? Thanks!

[TransAm 474]

The link below is what got me looking at the XFI lobes, I am very impressed with the result of his 461, and it very similar to what I'm wanting to do. That being said, his had 10.3 Compression and 310 heads and Performer RPM intake, instead of 11.0 compression and 325 heads and Northwind intake, like I'm looking at. That is the reason I was thinking I might be able to use a little bigger camshaft than he did, and maximize on the increased compression and head flow, but I may be completely wrong about that, that's why I'm here. All said and done, the result of his 461 is nothing short of impressive to me... it used the XFI lobes 3017B and 3038B, 236/242@.050 on 112LS+4 (108 I.C.) installed at 108.5 I.C. 597hp@5400 and 651 lb tq.

https://forums.maxperformanceinc.com...light=461+dyno