Balke

I finally had my 94’ Camaro dyno tuned today after being done and sitting in my garage for 3 years, and I was pretty disappointed. I know that all dyno’s are different and it’s not the best way to measure power but something seems off. The car ended up putting down 361 hp and 390 tq at 5600 and 3900 respectively.

The LT1 is a 383 with a forged bottom end, GTP stage 2 heads, GTP 6 Cam (similar to the cc306), 1.55 roller rockers, 54mm TB, 30# SVO injectors, TPIS long tubes, catback to a flowmaster with no cats, Street Twin, T56, and a stock 10 bolt.

I was under the impression that this cam was supposed to pull to 6200-6700. The power line gets wavy right about 5600 to 5800 and then starts falling off.

Could the valve lash be too tight? I am confused as I was estimating peak HP to be somewhere in the low 400’s.

I will try to post the dyno sheet when I get it emailed.

Balke

I have the dyno sheet but am unsure as to how to post it.
Thanks Colin

Balke

Could the cam be off a tooth?

Balke

Here is the graph, check it out.

MachinistOne

Host the dyno sheet on www.imageshack.us = then use the link provided to post it here.

You should be getting more rpm out of it, looking at the sheet will help.

If you cannot get that to work, email it to me


ehh...beat me to it while I was typing

MachinistOne

I don't see anything obviously wrong with that graph like ignition, valve float, VE or other...

What is your compression at?

Balke

It's been a long time but the compression should be up around 11/1 if I remember correctly.

I am thinking that maybe the cam is off a tooth because it makes tons of torque early and then falls out early.

MachinistOne

If it was a tooth off, it would run like crap - not just move the powerband around. What are the actual specs of that cam? Did you have the intake ported to match the heads?

Balke

Yeah the intake was ported and port matched. The cam is 235/242 @.050" with lift of .568"/.592".

AL SS590 M6

Flowmaster cat back can easily choke a motor down.

slomarao

ya but is shouldnt be that bad.

On the bright side you torque isnt that bad.
What did the heads flow? How much work does stage 2 consist of?

Balke

The second pull (in red) was with the cap off. It shows how much the flowmaster was holding back, but it still should be making more power than that.

GTP Stage 2 - Competition valve job, 2.00/1.56 valves, fully ported and polished then flow bench tuned for 280/210cfm

My flow numbers were supposed to be 278 and 210 @ .650

slomarao

Do you have a ewp, 58mmtb, etc? I.e. all the supporting mods?

WS6T3RROR

That is way too early a hp peak for that cam. Something in your intake tract is probably causing a clog. For whatever reason, your engine just stops making power and noses over. Did you verify that the throttles were wide open when your foot is on the floor? No floor mat stopping it about 10% shy is there?

About these heads of yours, did you buy them from gtp or were they second hand.... . There is a lot of bull**** going on out there with people passing off heads as reputable porters work and them just being cartridge rolled bs with chinese valves in them.

It would be great to see a datalog of the dyno run but i doubt you have that.

Balke

Yeah it has all the supporting mods (I have most of them listed in the first post). The heads were purchased directly from GTP so they are legit. I spoke with Craig today and he agreed that maybe the cam is off a tooth or maybe the valve preload is too much. I did not hear any popping in the exhaust or backfires, that would lead me to believe that the valves were hanging open.

If you look at the torque curve and how much power it's making so early on it seems like it's running an RV cam. hehe

I will try to get the data log and check out the TPS readings.