FWIW my GTP LT4 heads (stage II) flowed and performed as advertised as well.

With 300lbs of total pressure I doubt those springs are pacalloy - I don't think comp makes any pacalloy springs that light? I would go ahead and swap to some comp 977 springs.Though I agree 5000 definitely sounds low for valve float this would still be an easy thing to rule out.

As was mentioned, have you checked FP before? When you dynoed it were a/f ratio's taken? Also what lifters do you have? You might as well throw some comp R's into the mix if you haven't already.

Chris

 

Thanks guys. You are correct it was a CC XE cam, so the lobes were rather steep, but still... that was NOT a big cam. Exhaust is fine. Hooker LT's into offroad Y pipe, no cats and SLP dual, dual Catback. I don't think that is an issue at all.

I am running Comp R lifters already. Could the stud girdle kit or rev kit be taking any strength from the springs? I thought it was the other way around, i.e. you could run a lighter spring. Either way, it doesn't help much that I don't have part numbers. It's been a long, strange trip. I found the original receipt from GTP and unfortunately it was no help. It only says:
"New springs, retainers, keepers, seals, spring cups, guide plates", etc, etc, etc., i.e. no part numbers.

For cheap insurance, what springs should I use? I know the secondary fuel pump is working and a/f ratios were checked, but I am awaiting copies (still!) of that last dyno run. I will post it as soon as I can.

Thanks again
Mark

 

Mark

Mark

You could greatly expedite someone helping you by posting your dyno sheets especially if they have your AFR at the bottom.

Not everything will be obvious, but many items can be eliminated.

 

Well after 6 weeks of practically begging my shop guy, he FINALLY got around to getting my dyno sheet! I am about THIS close to just selling this POS and getting out of the F-body game altogether. If only it were that easy.

I scanned the PDF file to this location:
http://www.svt-enthusiast.com/albums/album05/mp.jpg

I hope you guys are able to see something that might help, but I can tell you that NO O2 readings were taken *Sigh* It just keeeeeeeeeps gettin' better, don't it!? They only used a scan tool to monitor O2's which were from .750mv to .830mv @ WOT.

The heads are back with GTP after finding the flow not up to spec. Is 280/215 going to be sufficient on a 396 to make 420rwhp/torque on pump gas without too lumpy a cam?

I await your feedback like a kid waiting for Christmas!

 

You should verify the AF ratio next time it's on the dyno. Are you sure the MSD box is not wired worng or mafunctioning and retarding the timing? A stock ignition should be enough to fire this combo, so one thing to try is running with the MSD bypassed.

Rich Krause

 

Air too. Probly not it but check for restrictions from the filter to the intake, throttle linkage and fully opening throttle plates.

Did you try a differant computer or program on it?

 

Thanks Rich, I'll check that as well. 96LTZ, I did not try another program yet. I wanted to get whatever issues this setup has settled before doing the dyno tuning. My motor guy doesn't think that it's possible to squeeze more than 20 or 30HP out of a dyno tune IF everything else is already optimized, so I am still short.

I see that Jordan stated in another thread that people are making 500rwhp with hydraulic cammed 396LT1's 'all the time'. I'd sure like to know how!

I am just stumped. I don't know what i have that is not right. The heads will be back soon (I hope), and then I have tochoose a cam and start the dyno tuning process.

 

First off, let's put a little structure into this problem thread:

1) List all your mods
2) If you are an A4/A3, was the converter locked on the run
3) If the dyno shop would not give you the sheet for 6 weeks, you need to dyno somewhere else.
4) You need to log a/f, maybe you need to dyno somewhere else if they don't have a wideband
5) You need to be shooting for a number, I would think a locked converter'd, hydraulic 396ci with 11:1 compression, with good exhaust should be hitting 425-450rwhp. But I am not an LT1 guy per se so maybe someone can better predict what are fair numbers.
6) GTP stuff tends to work pretty good, but more flow would be nice sounds like they will be pretty nice when done.
7) I think StrokerAce hit it on the head, either you are running out of fuel or your valvetrain has problems. I think you have valvetrain problems personally, I'd be putting on paper what springs you should run, the proper installed heighth, and I would also make sure you have the right lifter preload too. Your combo has that sound of having a few problems so you may need to take a few weeks and figure out what needs to happen.
8) Assuming you will only want to spin this motor to say around 6500 or so, that's up to you, you need to find springs that will work with your goals. One thing that works well is to find someone who has a combo that works well that is 90% of what you have. You can always compare the dyno graphs and numbers to see if you are going in the right direction.

 

Let me address each of your points:
1. Please see my very first post. It is quite lengthy and details all my mods.
2. It is not an A4, but an M6 with a Street twin clutch
3. It was not the dyno shop, but my speed shop - House of speed in Houston. Read Injuneers post too... this is a long, long ordeal. I have been royal screwed by more than one shop in Houston - this car has been off the road for 3 years now. I whish I knew someone locally who could take it in it's current state (torn down) and put it all back together.
4. I cannot do a data log or A/f now... the motor is torn down, the cam is out, the heads are back at GTP. They only used a scan tool to monitor O2's which were from .750mv to .830mv @ WOT, which according to HOS can be translated into A/F ratios, though I have no clue how to do that.
5. HP is right in the ballpark. When I chose all the components, I thought I should easily make 420rwhp. I don't think 450rw should be out of the question.
6. The GTP heads were advertised to flow 280/210. Recent flow test found only 260/212. Not too far off, but obviously not great. I expected (and want) great! We also got these numbers:
Intake cc - 183
Ehaust cc - 73
Chamber cc - 55
Craig has the heads back and has agreed to 'make them right'. Presuming I get 280/215 range, will this support that 420-440rwhp goal without too radical a cam?
7. Well noted - I am trying to get confirmation on all the part numbers. Craig's original invice did not list a single part number!
8. That is a problem. I have a Hydra rev kit and a stud girdle kit, so spinning up to 7K should be a non-issue. I don't know anyone else with all the same mods I have, and that is a big reason I am so flustered... I know people with less that are making a lot more power. All my shop guy says is that I have 'component issues' but will never elaborate beyond that.

I suppose once I get the heads back, have them flow tested again and have good numbers, I can come back with HP/tq goals, rpm range and request advice on all the valvetrain components and a cam. After that, I guess it's a matter of a dyno tune AFTER i check all the other stuff that people have suggested.

Thanks again
Mark

 

1. I read your post again.
2. Okay it's an M6 with a good clutch.
3. There are a lot of good places to go in Houston, you need to sort out your parts and game plan first.
4. ".750mv to .830mv @ WOT" is hella lean, you want the 02's, which are generally useful as a guide, to be in the 900-920 range. If you are super lean you can blow up your motor you need to dyno with a wideband don't cut corners. I wonder if your fuel pump is holding up. I would be using 36 lb injectors too, not 30's those are too small.
5. 425rwhp would be nice, anything below 400rwhp would be mediocre IMO.
6. The heads are not the primary reason for the low numbers. Your pistons must be in the hole eh to only be 10.8:1 with a 55cc chamber. Craig is pretty talented so it should work well, he's not typically who I would have pick the springs. Please also make sure you have a good 3 angle valve job after you have work done on any heads period; when in doubt take the heads and have them checked I always have mine checked by 3rd party now.
7. Ok.
8. Your big valvetrain issue is your valve springs. You need to partner with someone who can select the right springs for you.
9. You might want to see if your fuel pump is not keeping up, if your pump can't sustain the right pressure it will hurt your dyno numbers and it will lean out your motor to the point of potential damage. Put a gauge on it.
10. To play with fast cars you either need to pay folks market prices to build it for you or you need to learn this stuff on your own.
11. Your cam is small, let's shoot for 425rwhp not 450rwhp, I know of a car up here that was a 383ci hyd LT1 that did like 460rwhp and it has much more cam than you and it has GTP heads.

 

Great stuff John, thank you very much. I will follow up on all that information. Can you find out what cam that 383 is running and a basic mod list?

 

You can ask Craig on the cam specs, but the car in question has a GTP6 cam, it's M6, and has longtubes.

 

Mark

I can only feel for ya on this one. It’s probably something simple, so hang in there just a bit more.

I looked at your dyno sheet and frankly I can’t tell squat from it. The power curve sure doesn’t look like a 396 with only a 224/236 cam and heads that flow 260cfm is all I can say. Looks very odd to me for your combo.

If it was me………..

When you get the heads back from Craig (and I personally really like Craig) take them to another shop who owns their own flow bench and have them double checked for flow, combustion chamber cc and spring pressures. Ask their opinion.

Cams are cheap……. The GTP6 is 236/242 and I personally had great luck making 450rwhp with GTP LT4 heads and a Cam Motion solid roller 236/242 cam in a 396. 466 rwhp with a 240/250 solid roller cam. Being hydraulic cams tend to need less duration I'd give the GTP6 a try.

I personally had very bad luck with 224/230 and 224/236 Xtreme cams. (Yes, I know it pisses everyone off when I post this…… but I did!) I also personally had bad luck with solid lifters and would stay away from them. (Something else that pisses a few people off, but they didn’t pay for the three ruined engines like I did either)

Check the deck height of your block, go to the Atlanta F-body board and use their compression checker to see what it says regarding your compression ratio. While it’s down, I’d be real tempted to have someone look at your cylinder walls and rings to see if your getting ring flutter. Another symptom of ring flutter is oil in the TB and intake. If you see some (you will see quite a bit) then I’d check your ring situation also.

Put it all back together and get it on the dyno that has an 02 meter so you can check fuel/air and LT1 edit/Tuner Cat so you can change timing and fuel on the dyno. Make a couple of runs checking the fuel/air as your logs are very lean. Also check your fuel pressure (should be somewhere around 45psi) while it’s making a run to make sure your getting enough gas.

That’s about maxed me out for the time being. Keep a stiff upper lip (yes, I know it’s painful) but it will eventually get worked out.

 

Whoops........... One more thing.

Check your valve train geometry. (push rod length) There are cheap tools your can buy or have someone with a trained eye check the travel of the rocker arm on the valve stem. Decked motors, decked heads and/or small base circle cams can throw it off.

 

I'd put more cam in too since you are revising the combo.