GT-88 408 Dyno Graph inside. See what you think.
 

For those that have been following my build, here is the dyno graph. The bottom pull is the 408 NA, the next one up is with 6psi, then 12psi, then 17psi. As stated before there is something not right with the 408 and I think it is the fact I installed the VTC-3 cam at 105 ICL, not were Virgina Speed wanted it, my fault there. I am goign to move the cam to were they want it and I expect to see the NA numbers come up. If you have any ideas, let me know and I will look into them.

i have doubt from the cam it should not be reverse patten

My first thoughts are that you N/A numbers look pretty good considering you are running lowish (guessing here) static compression, with all big flow type intake, exhaust. I would definitely set the cam as suggested by Virginia Speed.

Yeah those numbers are a little off. I havnt seen the other thread I dont think so Ill go check it out. Cr? I am guessing that the cam is alot of the issue.

Are you in Austin? Nice #'s!

When built, I requested 10.25:1 compression. Now when I picked it up the builder was thinking it was 9:1 compression, so there is a little confusion there. From the time he ordered the pistons to the time the engine was completed was about a year, so by that time it would be understandable if he forgot what the compresion ratio was. I do have the build sheet and plan to get the piston part numbers and call Ross up and see if they are in fact -12cc pistons or something else. I plan to find that out before I move the cam this weekend. If they are lower compression pistons then I am thinking, and in the 8.5:1 to 9:1 range then I guess those NA numbers are were they should be and I need to move on to other things like moving the turbo up front to get rid of the lag time. If the compression is lower then I think it is it would explain alot of things, like the lag time, the fact I can run 38 degrees of timing before boost and see not knock, the fact that I can run 28 degrees of boosted timing with no knock (we have the boosted timing at 18 degrees right now).

The lack of power down low can only be from low compression, now if it is due to static compresion from the piston -cc or dynamic compresion from were I put the cam I am not sure wich. It very well could be a combo of both.

No, I do not live in Austin, I am in South East New Mexico. I pulled my car down to Austin this Thanksgiving Holiday for tuning, and my mother lives in Manor.

That's pretty much what I was thinking. (8.5-9.0) static compression, combined with the ICL of your cam.

Btw, how is Hobbs nowadays? I used to live in Tatum back in HS

I have been here 5 years and looking to move back to West Texas the first chance I get. It has grown, we have a Super Walmart now (granted it can not stay open 24hrs a day because they can not hire enough people that can pass a drug test), we have an Ihop now (same problem as Walmart), we have a Lows and Home Depot now too. They are building a Tractor supply, but I bet they too can't find employees that can pass a drug test.

Yeh, pretty much the same as it ever was. Their Basket Ball team is still kick ass.

Man I would have killed for an IHOP when I lived in NM. Other than Allsups, you were SOL at night if you got the munchies!

Oh, congrats on the boosted #'s, they look very nice!

What fuel are you running with all 3 boost levels? Also nitrous is always an option to help you out down low. :)

Super Unleaded, 91 Octane pump fuel.

Seems pretty damn good, some cars just dont put down huge numbers like others, or some dynos are stingier?? My car doesnt dyno for shit compared to how fast it goes at the track, I wondered about my dyno numbers too. Seems like some cars not weighing much more but making 100whp more with the same setup go slower.

91 octane? Seriously?

Run Torco at the bare minimum!

You might as well be running 87. You cannot make close to 1000 rwhp on 91 and expect your combo to last long. Obviously there are a few exceptions out there, but LS motors do not seem to be one...

Also, consider the rear end, trans, etc etc. It doesn't sound like you built this combo for the dyno. Take that thing to the track on some 116 and see what it really does.

Get some decent gas in there. Let me know next time you come down to the ATX©.

-W

Reading the thread and the last and looking at the dyno sheet leads to to 2 things.

1-the cam is not in fact on a 105 but maybe closer to a 114-115 icl. an advanced cam will make more cylinder pressure which should in fact make more low and and kill some top end. Also the tuner said he had 30 deg of timng in. if the cam was too far advanced it would spark knock before that much timing.

2-the intake runners are far too big for a rearmount turbo on that size of an engine. a 225-235cc intake runner would make that engine far more happy.We've made 1800hp with an ETP 225,no need for a huge head.

Dude NOTHING beats Allsups chimichangas at 3am!

true, very true :)

Am I seriously the only one thinking the shitty, dirt filled, so called 91, New Mexico hog wash fuel could be the culprit?

Seriously?

You guys are reaching for extremes when it could be very simple. I have seen DRASTIC increases by simply changing to 91 and Torco. I have seen multiple cars trailered in from West Texas (and New Mexico) to Dallas and people being PISSED with the results.

I'm agreeing with Shawn, if the cam was on a 105 ICL it would help spool up, but fall off on top.

I have also run VP 113 in it. No difference. It is not the fuel.

I understand what Shawn is saying. At 105 you would expect the power to be down low. It is very strange that the torque curve (NA) is really very flat and carries up top. BUT, when I installed the came I checked it multiple times. That is what threw me off, I was expecting it to be at a 111. Now that said, I am human, and I could have screwed up my readings. This is not the first cam I have degreed, I never install one without checking, but it is the first LS cam I have degreed. If it is any different then doing a SBC, a BBC, an old school Pontiac, or a Mopar, then I need to be schooled on the proper way to degree a LS Cam. I am human and could have screwed it up, but I am 99.9% positive it is on a 105.

The thing that is in question is the compresion ratio. This is the first engine I have ever had someone else build. I was too busy to deal with it. I requested it to be built with 10.25:1 compression. When I picked the engine up I was told it was 9:1. So what it is I really do not know. If it is a 9:1 build, then the low NA numbers make sence I guess. I can tell you with a compresion gauge it makes 155psi. I was expecting it to be closer to 200psi. That is what it was with less then 200 miles on the engine and it is the same today with this cam.

Let me refresh some history with this 408. It was first built with a 230/240 114 .60?/.60? cam. It had a GMPP single plane EFI intake with and Edelbrok low profile elbow (100 degree). Hooker LT headers, no Cats. The car had a 4L60 with a 3500 stall, and 3.73 gears in it. It would only run a 12.73 ET at 115mph at our track. My old original 346 with a MS3 would do that and more. So I started looking for the issue. I checked the cam timing, compression, pulled the engine and took a look inside, and I could not find anthing wrong. I decided to go ahead and install the turbo.

I got the turbo on and it had terrible lag. I bought the VTC-3 cam, same performance and lag. I pulled the intake off and switched to the LS3 intake thinking the elbow was killing me, same performance and lag. I pulled the headers and installed the iron manifolds, same performance and lag. I checked for leaks, 4 different times. I changed the piping some too, still no improvement. I then installed a 2-step, nothing good there. I then had the 4L80 built with a t-brake, now with that, if I stand on the T-brake for 5 seconds I can build 6 psi of boost before launch. Some were in there I swapped rear ends to a Moser 9" with 3.70 gears. I tuned it, others tuned it via email, I had it tuned, still no improvement in performance or lag time. This 408 is symply a gutless wonder without the boost. There is something consistent with the engine causing this. It has always been like this. That is starting to make me think of something like compresion ratio. Now that said, I could have screwed up the cam timing, but it is very unlikely. I plan on checking it this weekend and moving it to were ever Shawn suggest it to be.

Yes, on the dyno we did add timing to it (NA) until we got to 33 degrees or so, well over 30 degrees, at WOT and not once did the knock sensors pick anything up, nor did I hear any pinging, nor did it puff any smoke out the exhaust like it was experiencing detination. When the 408 was NA with the other cam in it I had the timing up to 28 degrees at the track WOT and never had any knock.

I really think the compression ratio is 9:1 or maybe even lower. That is the only constant thing that I can think of that all these things leed to. I am going to get my build sheet out tonight and get the piston part numbers and post them up.

Be right back.

OK, here is the specs on my old cam, IO 1 BTDS, IC 49 ABDC, EO 54 BBDC, EC 6 ATDC, as mesured at 0.050" Advertised duration 292/296, 0.050" duration 230/240 lift .593/.602 LSA 114, cam manufacture Herbert Cams Part# LS1-RH3-360.

On the pistons all that is on the build sheet is Ross Pistons 12-32.
Timing set is a Cloyes CLO-9-3159.
Lifters are GM Performance Lifters part # 88958689.
Head gaskets are Comitic #C5751-040.
Block was also decked but it does not say how much.

These numbers do not tell me much. i will call Ross tomorrow and see what they say.
Here are the picks of the pistons. maybe someone can tell something from them.