not making the power it should suggestions?

[rennocneb]

Ok,

New engine 434ci stroker dry sleeved. 237/247 eps cam. ls7 lifters, tea stage 2 heads, .660 lift springs around 180 on the seat 470 open pressures. ls3 intake, ported ls3 tb, kooks long tubes, rotofab. The thing is only making 420whp in 3rd gear, slightly less in 4th??? it has some valvetrain noise but otherwise sounds STRONG. but its able to idle at 550rpm and acts like its got a small cam minus the big torque that goes along with it. the one thing i wander about is it has 7.300" pushrods. Could these be to short to the point its killing power? and causing the valvetrain noise? im open to suggestions its just down on power but everything seems good.

[Boostpatrol]

Who built this motor? It is way down on power considering the LS2 6.0 i have in my car now with a stage 2 cam makes 440whp on manifolds and 2.5" exhaust. They should also dyno in 4th gear which is as close to a 1:1 ratio as the G8 gets.

[Slizzo]

Ok,

New engine 434ci stroker dry sleeved. 237/247 eps cam. ls7 lifters, tea stage 2 heads, .660 lift springs around 180 on the seat 470 open pressures. ls3 intake, ported ls3 tb, kooks long tubes, rotofab. The thing is only making 420whp in 3rd gear, slightly less in 4th??? it has some valvetrain noise but otherwise sounds STRONG. but its able to idle at 550rpm and acts like its got a small cam minus the big torque that goes along with it. the one thing i wander about is it has 7.300" pushrods. Could these be to short to the point its killing power? and causing the valvetrain noise? im open to suggestions its just down on power but everything seems good.

Need to know what other mods were installed at the time the new motor was dropped in.

[rennocneb]

just the engine. it was a complete long block from the builder.

[rennocneb]

well engine and stall

[GRRRR8]

I would like to think this is a 500rwhp combo.

The pushrods do sound short. 7.350 to 7.400 seem to be the norm. Depending on if the block was decked and the heads were milled, that would tell how much shorter they might be.

What is the compression supposed to be?

[laserred]

Without hearing this "valvetrain noise", it's hard to say. Plus, it's been said a thousand times and will be said at least a million more, dyno numbers are just that, only a number. Don't be so worried about what the dyno says as long as the car is fast at the track, where it matters. Many a dyno queen has gotten their ass whooped by somebody who had a lower number. Depending on the converter and condition of your trans, it could be eating 50HP or it could be 150HP.

Get it to the track, with a good tire to eliminate starting line slippage. Then beat the hell out of it. If it goes faster than 12.40 and/or 110 mph, the dyno is skewing your reality which is that your car is making more power than it says. Don't get caught up in a game you'll never win; the dyno shouldn't even give out HP/TQ numbers- it should only give out AFR and BSFC! LOL

[Patrick G]

If the heads have not been milled, if the block has not been decked, and if you're running stock head gasket and rockers, the proper pushrod length is going to be 7.425". So even if you've had some milling or are running a thinner head gasket, I estimate your pushrods are entirely too short.

[rennocneb]

its running TEA stage 2 l92 heads im trying to verify how much they were decked but i told them minimal to clean them up only. its around 11.5:1 compression, and the block is never decked more than .005 according to the builder. it is running cometic head gaskets not sure on thickness but they are what at the thinnest .040? versus .055 stock i think?

[johnbell2]

This sounds familiar... I went with 0.040 Cometic gaskets on stock heads / rockers and pushrod length went to 7.400

[rennocneb]

yea 7.400 id buy because the block has a minimal few thousandths cleanup and the heads have had a cleanup plus the gasket, so 7.375 or 7.4 makes sense but not 7.3. my question would this account for missing horsepower and torque?

[todds87ss]

Seems like you went to a lot of work to not use a pushrod length checking tool. Get the right measurement, just to be sure. Don't know how much you are leaving on the table, but it would make the cam seem small.

[rennocneb]

if you had read the thread. i bought this engine from a very well respected shop not gonna say who. They measured for the pushrods, i just think maybe an error got made ordering them or something.

[johnbell2]

yea 7.400 id buy because the block has a minimal few thousandths cleanup and the heads have had a cleanup plus the gasket, so 7.375 or 7.4 makes sense but not 7.3. my question would this account for missing horsepower and torque?

I'd listen to Pat. Then I'd work with your engine builder and double check parts.

[rennocneb]

7.400 pushrods are in it, valve train quited right down, the car picked up a ton of lope at idle, but the power still peaks at 5800 and it makes the same at peak as it did before. WTF?????????????????????

[STL_G8GT]

What does the builder say? You paid them to build it, correct? Id be looking for more than free advice on a forum if it was my chunk of change on the table! :-)

[vic2186]

U should be In the 525+ range with a dry sleeved 434ci that's a beast motor and 500 plus torque

Ask him what's up!!

[Slizzo]

OP said on other boards stock fueling but nit maxing injectors... I still think that's not enough?

[G8-4-Speed]

Could be too much cam and too small of an intake. The larger motor drops the rpm range compared to a 364 motor so your peak Hp will drop. You can't make HP without RPM. You need the right duration, ICL, and LSA with some greedy lift to make it work with a 434. Drop 7 degrees off the intake, 10 off the exhaust. Put the intake on a 112 ICL on a 115 or 114Cl, get the lift in the .620"+ range, and it will pick up at least 20Hp. Ported or not, if you haven't changed the cross-section or length of the LS3 intake runners, then don't expect 6800 rpm out of that motor. You wanna make power, then put LS7 heads and intake on.

[GRRRR8]

Stock mufflers could be choking it a lot and so could cats. I have seen this on 364s and 376s. Stands to reason 70 more cubes is going to need to let out a lot more air. You should be running 1 7/8 headers minimum as well.

[rennocneb]

No cats, no mufflers, kooks 1 7/8 hearders. Surely the ls3 intake would make some more than what it is.

[johnbell2]

Stock MAF? What's your MAP readings say?

[gtp6515]

Update?