Spring recommendation for GN1s

[jpwalt1987]

The noise is determined by the lobe. I have noise in my black car and very little noise in the blue car. Same lifter. The cam is a small .530 lift love on the blue car. The black car has about .600 and I'm using considerably more spring to control it. If you want it quiet put in a cam with no more than .290 lobe lift/.450 net and run a spring with 120 on the seat and 350 over the nose. I've never heard any ohv v6 engine that made 2.5hp/ci or more with a quiet valve train.

I don't really care if it is whisper quiet so long as it makes the power. It has an old 1998 era 70mm Garrett turbo. It is rated at 775hp and I would like to max it out on 93/alky.

 

[bison]

I don't really care if it is whisper quiet so long as it makes the power. It has an old 1998 era 70mm Garrett turbo. It is rated at 775hp and I would like to max it out on 93/alky.

It's probably a t70 with a 76p ex wheel. Which compressor cover? The 76p seems to crap out around 75-78lb/min. The compressor will go 90+ with the correct comp housing. This is assuming the engine will flow it. If it has the old t04s04 cover then you are in luck. Just convert it to a GTQ and it will have the 90+lb/min potential.

 

[jpwalt1987]

It's probably a t70 with a 76p ex wheel. Which compressor cover? The 76p seems to crap out around 78lbs/min. The compressor will go 90+ with the correct comp housing. This is assuming the engine will flow it.

The compressor cover is 3 inch inlet and 2.25 outlet(I believe).

Here is a link to my old webshots page.
http://rides.webshots.com/album/553557263NNgwpB


The motor should flow way more than this turbo can dish out.

 

[bison]

The compressor cover is 3 inch inlet and 2.25 outlet(I believe).

Here is a link to my old webshots page.
http://rides.webshots.com/album/553557263NNgwpB

The motor should flow way more than this turbo can dish out.

Thats the best cover you can run with that compressor. Once you hit 137-138mph you will hit a lot of back pressure. With just a turbine change you can get another 15lbs/min out of it. It will take 28-30psi to get the 78lbs/min out of it even with the 76p turbine so you have a lot left

 

[SloGN]

Not enough spring. I run PAC 1203's with any hyd application with a fast ramp/high lift that will be over 5500. I run zero lash/zero preload on 885 lifters. Some of the slower ramp profiles could use a solid lifter with a tight cold lash around .006 and make a little more power. Your engine should be hitting peak power at 25-30psi around 5500-5600. Not laying over there. It should carry it within 10% all the way to about 6100 too. So if you had 650whp@5500/27psi it should still have about 590whp@6100. I personally would never run a cam that peaks that late with a stock crank/rods. 212/212 will peak around 5100 and you can play with tire height if you have a good coupling converter and run 136-137@ less than 5800rpm. With the 218 intake lobe you need a flash stall of at least 5300 to really throw it in the power band. Anything that will get it close to 5500 as long as possible will make it quicker once you get the problems sorted out

Bison

How much spring do you reccommend? 160-170 on the seat and 350-370 open?

 

[bison]

Bison

How much spring do you reccommend? 160-170 on the seat and 350-370 open?

The comp 26120 conical springs would be about the least I'd run for that cam. Ive ran them up to .550 lift/6000rpm sucessfully.160-170 on the seat and about 450 open. There is no point in putting in a marginal set of springs.

 

[Quik Six]

The comp 26120 conical springs would be about the least I'd run for that cam. Ive ran them up to .550 lift/6000rpm sucessfully.160-170 on the seat and about 450 open. There is no point in putting in a marginal set of springs.

Well, this thread ruined my day. I felt pretty good about the 10.37 ET and 132 MPH run with a crappy 60' of 1.58, less than 25#'s of boost and 3 broken teeth in the ring gear. Really looking forward to running 10.0's in a couple of weeks. Looked up the springs that came with my kit from DLS and they spec'd at 130 on the seat and 350 open. Pull up the PL file and looked at the MPH graph real close and notice 3 flat spots: stayed at 109 and 5313 RPM for .360 seconds, 123 and 5585 for .540 and 127 and 5616 for .360. Time slip shows ET for last 1/8 was 3.729 seconds and MPH gain was 27.11 despite the flat spots.

Been down the valve float road before and this looks all too familiar. I do want to give the Morel lifters another shot before I replace them. I'd appreciate your view on springs above "the least I'd run" ones you mentioned above.

Thanks again.

Phil Engle

 

[toomanymodz]

I spoke with Weber a few months back and they had a car with the same issue. They DID attempt to change spring pressure and it did not help in their case. This is why I had dismissed the possibility of valve float. I'm out-of-state on vacation right now so I don't have access to my build sheet, but I think that PAC 1200 springs were installed in my engine. If I could just get 300 to 400 more RPM's outa this thing I'd be happy. A 5600 RPM shift is what I'm looking for. I'm a bit relieved to see some other folks coming forward with the same issue. Perhaps one of us will find the root cause.

 

[Quik Six]

I spoke with Weber a few months back and they had a car with the same issue. They DID attempt to change spring pressure and it did not help in their case. This is why I had dismissed the possibility of valve float. I'm out-of-state on vacation right now so I don't have access to my build sheet, but I think that PAC 1200 springs were installed in my engine. If I could just get 300 to 400 more RPM's outa this thing I'd be happy. A 5600 RPM shift is what I'm looking for. I'm a bit relieved to see some other folks coming forward with the same issue. Perhaps one of us will find the root cause.

Send me a recent PL file of a full run at pengle@cox.net. I've had pretty good success at helping with problems with combo's virtually identical to yours.

FYI, RPM of shift points on 10.37 run were 5993 at 46 MPH, 5850 at 86 MPH and crossed the line at 5748 at 132 MPH.

 

[jpwalt1987]

What I am going to do is buy a set of comp 885 lifters and correct pushrods. I will install them then look into increasing spring pressure. With what my converter is flashing to I believe I need the ability to turn 6500 rpm or so.

 

[bison]

What I am going to do is buy a set of comp 885 lifters and correct pushrods. I will install them then look into increasing spring pressure. With what my converter is flashing to I believe I need the ability to turn 6500 rpm or so.

If your engine is capable of 6500 in 3rd you're trapping 155mph.. At that point you're better off with solid lifters. They are much lighter.

 

[jpwalt1987]

If your engine is capable of 6500 in 3rd you're trapping 155mph.. At that point your better off with solid lifters. They are much lighter.

Well I don't think it will run 155 with what I have so I guess I don't need to turn 6500 out the back. I am hoping it will go about 138-140. I may have to have my converter changed up then. Idk. One step at a time

 

[bison]

Well I don't think it will run 155 with what I have so I guess I don't need to turn 6500 out the back. I am hoping it will go about 138-140. I may have to have my converter changed up then. Idk. One step at a time

If you can't get it done under 6200 then something is wrong. My car has enough power to trap 140+ and it likes being shifted around 5900-6000. About 6000-6100 out the back. Max power for me is 5500-5600 with a 218.

 

[toomanymodz]

I wonder how many additional RPM's titanium retainers would give. I also wonder what the weight comparison is between Morel lifters and the comp 885's.

Hey Quik Six, I sent you a PL file.

 

[SHADOWII]

I believe that my knock shows up because of rpm and valve train noise. My tune is real safe. 10.2 AFR 18* timing and alky maxed out. Plugs told the story of no knock. I had a solid roller cam before that would pull to 6500rpm all day long and didn't cause any noise induced knock retard.

Is there any possibility you are running too rich w/combination of fuel and max alchy?

 

[bison]

I wonder how many additional RPM's titanium retainers would give. I also wonder what the weight comparison is between Morel lifters and the comp 885's.

Hey Quik Six, I sent you a PL file.

The weight is similar. The plunger on the 885 has limited travel and will tolerate the higher spring pressure better. The weight saving with titanium is negligible.

 

[bison]

Is there any possibility you are running too rich w/combination of fuel and max alchy?

I don't see how this could be if he's at 10.2:1. I run about the same target with two 10gph nozzles so on the same gasoline scale I'm even richer than he is because I'm injecting less alky. I'm using 810-820hp worth of fuel. Assuming the gas is 10% ethanol and 90% gasoline and the additional alky I'm injecting.

 

[toomanymodz]

The weight is similar. The plunger on the 885 has limited travel and will tolerate the higher spring pressure better. The weight saving with titanium is negligible.

Perhaps I could try adjusting to zero lash? Also, jwalt1987 mentions that he has knock at the moment of float. I have the same. I checked the PL file and I had an AFR of 10.97 to 1 at the moment of knock (17 psi boost, 93 octane no alky), so I don't think it's due to a rich condition.

 

[NCTURBOS]

http://m.summitracing.com/parts/CCA-26926-1

These are the springs that are being used right now.

I've had very good success with this spring and the 885 lifters.

K.

 

[bison]

Perhaps I could try adjusting to zero lash? Also, jwalt1987 mentions that he has knock at the moment of float. I have the same. I checked the PL file and I had an AFR of 10.97 to 1 at the moment of knock (17 psi boost, 93 octane no alky), so I don't think it's due to a rich condition.

I would run zero preload. Jwalt isn't sure if his problem is valve float either.