I've been helping 35 spline with his setup.
We only have about 20 miles of driving on the whole turbo and fuel injection setup. the main thing was to get it running and moving. Once we started getting on it a little we found that it just doen't feel right. turbonetics suggest twin 60-1 turbos with a much smaller exhaust wheel and AR. However everyone else says bigger. Precision wants to keep the 72's and change the exhaust side to P trims and .81 or .63. What they really want is to pu ttheir billet wheel stuff in it of course. Everyone this big is using an auto and most are race type stuff. This car is a stick which not only makes it much harder to tune it also makes the turbo spool tougher. Right now I am really leaning toward P trim and 63 or 81 housings. Tuning in the Texas heat and trying to find a driver willing to sit in a non AC car while I watch the laptop and tweak it is tough. Until we get it most of the way there dyno time will be a waste. My claim to fame is Grand Nationals and had one making 850 to the wheels rom the V-6 and a single 88. I have played with Accel gen6, Big stuff, Classic Fast and XFI, but the Accel Gen 7 and thruster is a little new to me. we are playing it safe and timing maxes at 34 no boost and 26 degrees at 7 pounds. Nothing richer than 12.0 Again, main concern is getting the car sorted out as the OP did all the work and I met up with him after the fact and am just offering help. Going out and full throttling this thing would not be the smartest thing to do, so we are taking it easy.

Greg

 

you are 25 mins away from me. if you need help with the tuning, I will be more than happy to help. even if its just sitting there in a non AC car lol. I might need help with my efi tuning later this year

 

P trim .81's may work ok. Just not 100% sure since thats a huge motor with a ton of air flow going thru it. I would have expected that motor to spool up those 72's much quicker than they are now.

Since you are not turning high rpms, P trims may solve your problem and get much quicker spool at the expense of limiting top end hp.

 

Well you gotta figure guys are doin 600+whp with p trims so 2 of them should get to 900hp right?

 

There are guys here running well with the P trim so yeah, it can handle some flow but who knows what pressure thats at. I never measured the backpressure on my setup and I didnt expect a problem but I am getting some crankcase problems that may be from several non related things. I have to check.

I just wouldnt want to see alot of back pressure in the system from a small turbine side.

 

I do know BBCs LOVE timing....typically a 10:1 motor will want 36 or 38 total (N/A application). Maybe try 38 total at ~100kpa and ramp down from there (a little slower perhaps). I would probably expect 26* at 10-12 psi of boost. Keep it lean (13:1) until it starts building positive boost then richen it up possibly.

Also once again, I would pressure check both the cold side and hot side for leaks.

 

Just a quick suggestion: you're running 14.7:1 at low MAP (like 30-40 kPa), right? If you're running 12:1 all the time, that would probably make it feel a little doggy. You might also go with a little more aggressive timing down low, like 38 from 2500 to 3500 and get closer to stoichiometric. To make the turbos spool more quickly, you can also pull 20 degrees of timing out of it at 100 kPa MAP which will raise the exhaust temperatures (at 13:1). As soon as it goes into boost, fatten it up to 11:1 -- but you know that from your GN. Still, a 9.2:1 540 inch motor with a manual transmission in a 3300 pound car should not be "sluggish". More like scary fast, then more scary fast as the boost comes up.

 

Got a little datalogging in today. 2nd and 3rd gear pulls. 2 pounds of boost at 3300 rpm and 8 pounds on the wategate setting at 4400 rpm, took right at 1 second to get there. Lugging it down to 2200 rpm and just flooring it in 2nd yields very unimpressive acceleration, almost nothing happens. I think the p trim and .81 AR will be workable and worth the rebuild costs.

 

Here is an update. Took the turbos to TurboDaves in Dallas and found out the swapping the Q trim to a P trim is impossible. The only option is to keep the Q trim and get smaller AR housing for $300 each. I am not sure how much this alone will help so I am looking into a a cam swap. Here is what I have now

 

I'm with these guys Even though that's a ton of turbo for the application (especially with your desired redline) you really need to consider your timing. If you're running 26 degrees in the N/A fields on moderate compression aluminum headed engine you're probably going to have boost threshhold problems.

 

First off I'm going to apologize for sounding crass. You have an absolutely unreasonable expectation of your combination. If you wanted it to pull from 2000 rpm, why did you put a big head and a huge cam in it? It says right there on the card MINIMUM rpm 3100. It's making 2 psi at 3300 and gets to 8 psi and 4400 in one second, that's not bad for a tune that's 10 degrees shy on timing. The parts you have match, they are working well together, they will NEVER be able to do what you are asking of them. You have a stick so there is no torque converter to help you load the motor and the turbos. This fact is amplifying your problem. What's the rear gear? In my opinion to get your setup to do what you want it to do, you need to put the smaller housings on first. They WILL move you toward what you want. 2. Put some more timing in it. 3. If those two things don't make you happy with it, it's time for a cam swap. Get something with 20 ( yes twenty) degrees Less duration on the intake, tighten the split from 12 to 8 degrees, and widen the LSA to 116. Somewhere between those 3 things it should start acting like you want it to.

 

I am not running timing that low in the N/A field. It is more like 34-36 deg before boost starts.

 

In an earlier post I tried to show my timing table and it was too small to read. I have corrected that and will repost it here. I do not see where my tune is lacking 10 degrees of timing. Constructive comments on my timing curve appreciated. I agree the cam is too big and not optimal for a turbo car and what I want it to do. I had installed the cam back when it had NOS and it was mostly a track car.

 

Ok I take it back. Lol now that I read that, I was wrong in what I said. Was going off numbers said earlier in the post.

One trick I learned concerning timing and helping spool is to not start taking timing out right away. Instead of pulling it starting at 1 psi, wait till 4, then ramp out the same amount by 8 so you're still at the same number as before. This really helped a 421 sbc with a 94mm I helped out on for a friend. Obviously you gotta check reall close for detonation.

 

These two things are the issue the wrong (you know) and the timing. your at 30* at 0 vac/bst at 2 psi your already down to 28*.
Even if you did start at 36 and you drop to 24 at 14 psi that is a 12* drop but it is too aggressive and too quick.
I would like to see the AF if it is on the same fall rock scale no wonder it didn't perform.

Also the between shift A/F and Timing is important with a stick. You posted this on YB?

 

I think you are correct about the timing. I think it should be at 38 degrees above 2500 RPM and 0 vac based on another N/A 540 I have. It picked up 30HP on the engine dyno just going from 36 to 38 deg of total advance. How much should I reduce the timing at full boost (8 psi)?

 

Spline how about more pictures of the engine from different angles and some close ups of the injection. Sweet ride for sure.

 

I am going to be on the phone tomorrow calling cam companies for their turbo cam recommendations. Comp Cams has already responded with a single duration HR cam with 235 of duration on the int. and exh. lift at .647 and lobe sep at 115 installed at 112. At first this doesn't look that much different from what I currently have except the exhaust duration is 21 deg lower than the current 256 @ .05

 

Watch the boost gauge in this video,
It's the 2nd one over from the tach.

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I'm surprised the needle hasn't broke off for all the times it has pegged it.
The engine is 540 ci. 8:1 compression, 75mm BW turbos with 1.32 A/R turbine housings.
The two 60mm wastegates open at 12# and it overcomes the open holes to still make 27#.
I don't feel I have any spool up problems here.

My cam is pretty close the one posted.
.630 lift, 116 lobe center, duration at .050 is 256.

FAST E85 ignition table,
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Looks like you have a lot more timing than me. You are at 35 deg at 0 vac and only drop to 34 by 17psi if my Kpa to psi conversion is correct. Probably due to the E85 having more Octane? I have my fuel system set up to run E85 but I started tuning with gas just to get it moving. I plan to eventually move to E85.