frcefed98

iTrader: (16)

I want to help spool this GT42-74 anyway I can. Would I benefit from taking off my Magnaflow catback and just running a straight pipe from my DP and dumping before the axle, maybe running a bullet muffler to quel the noise some?

I REALLY LIKE the ATP boost activated cut out, but man its expensive, but it would be easy to weld that directly to the DP and out the side of the car infront of the front tire

Loose the magna flow, run a straight pipe with a nice bullet muff or just get the atp boost activated cut out??

**** i'm almost thinking this GT42 is too big, T70 would be a quick spooler for sure.
J

Smearin

I know that by taking off the catback.. you would decrease the B.P on the turbo... I dont think it would have much effect on the spool tho.. it would just take some of the load on the turbo.

I would suggest running an BOrla xr-1 muffler.. which is straight through

W8N2SQZ

iTrader: (6)

Jer,

I had the same thought as you on the DP off the turbo and then dump it infront of the front tire. The problem is, if you ever lose the motor, all the oil will be dumped infront of the front tire and man that would be ugly. I didn't want to do that on the freeway somewhere and make things worse either.

I read on here once that a guy with a PTK corvette kit said his spool time increase a lot once the cat back was dropped on the dyno

Just food for thought,
Glenn

anarchy99

iTrader: (7)

You would lose some weight though on the car if you ditched the cat back...

bboyferal

iTrader: (9)

Loudmouth here... a cut-out is always nice but you can't go wrong with a good bullet.

lcvette

iTrader: (3)

you WILL decrease spool time by minimizing the back pressure of gases escaping from the turbine. so yes the best spool characteristics will be had with the most non restrictive downpipe that is designed to basically get the exhaust away from anything it could damage.. the fewer turns the better. the other thing I am wondering as I am running a precision T74 GTS on a 355.. where are you seeing your peak boost, and boost start? mine is the smaller housing setup to the GT42 74.. and I am just curious to how your setup comes on.

Chris

ps.. there are a few tricks you can do in the tune to help get the turbo moving.. they like to have timing a bit less advanced down low.. this tends to put the egt's a little higher and finish partial combustion in the primaries.. sort of like an afterburner.. a little fatter also doesn't hurt.. just some ideas to play with.

Smearin

Ah.. thats what I thougt.. thanks for clearing that up..

frcefed98

iTrader: (16)

Cool, really thinking about dropping it. Dropping weight off the car is a good too

Just hope it isn't too loud, I don't mind the extra noise, just don't want the cops to be swinging off my ***** for it.

Glenn thanks for giving me that lil bit of info, didn't even think about oil dumping out of that biotch...especially on the track

I had a LM back in the day, but it finally wore me out. I guess that if I want to get any advantage that I can, it'll have to come down to a bullet and some straight tubing....glad I have tons of 3ft sections of SS here...just need to buy a bullet.

I did drop the timing down some in the midrange, but I have it stoich when the timing drops, so I should richen it up huh?? I can always drop the timing more. This sucks because I really don't know the ins and outs of turbo tuning just learning as I go, so thats probably hindering me big time.

Turbo starts spool around 3-3200 now and hits it peak at 4200 on the track.
J

lcvette

iTrader: (3)

on a front mount? yeah you can definately help that thing out to come online a little sooner by adding some fuel down low.. where about is your timing at 100kpa in those rpm ranges? running it a bit less advanced is not going to hurt your torque down low too bad.. engines generally like more advance as they are spinning faster.. it is designed to account for the burn rate of air and fuel being a constant and as the engine allows for less time during the combustion event at upper RPM's it needs to start the flame propogation sooner. at 1500-2500 there is enough time to run it extremely mild with little to no ill effect.. just stick to the 100kps tables and maybe a little under them so as not to hurt your MPG's while at cruise and light part throttle operation. once ya mat it though.. your not really concerned about those things.. you want the turbo to come online as quickly as possible.

I know you are not too far out from getting this thing up and going, but have you really gone through the hot side plumbing to make sure there are absolutely no leaks and the wastegate is seating properly? that seems a bit high for peak boost on a 74. I would imagine vacuum/boost transition around 2700 with peak somewhere around 3800 max with all things perfect.

Chris

SScam68

iTrader: (20)

Hey ********, I told you you could borrow my 2 step.

At this point you need it more than I do.

LSs1Power

iTrader: (5)

If you want to increase the EGT to spool the turbo faster you need more timing down low and running a little bit lean. Just watch that KR when you are trying to do that. Good luck

smokinHawk

iTrader: (48)

you could always just put a manual cut out on it.

SUPER DAVES Z

iTrader: (6)

That'll cost you a whole $35 and I think you'll be surprised how big a difference it’ll make.

JZ 97 SS 1500

iTrader: (2)

The 42-74 will spool fine on your car. Just add a cutout and some fuel for some added heat. You'll see/feel a nice difference.

Jose

frcefed98

iTrader: (16)

Thanks for all the advice guys.
I'll be going through the hotside parts this saturday, checking for leaks. I'll test the WG out. Should be able to do that with a mityvac right?

lcvette/jose, I'll check my tune out in those ranges...see what I have going on. I know I took fuel out of the midrange and the car picked up acceleration wise, but I'll go the other way and see what happens.

Frankie, i'll ask to borrow that bad boy when my new tranny gets here fo SHO!! Just waiting on that, no need to get hostile...

Bah, manual cutout, I want a things to do it themselves Boost actuated cut out will be mine as soon as I sell some blood.
J

80superbu

iTrader: (8)

Any updates??

FastKat

iTrader: (10)

Hey, not sure if you've already addressed this, but are your headers/manifolds coated? I am wondering if a GOOD ceramic coating would help... something like Swaintech, who seems to have a pretty serious and unique product.

frcefed98

iTrader: (16)

No haven't had a chance to work on the exhaust yet. I replaced the tranny yesterday with help from my Dad, bro and uncle We also swapped out the BMR T/A and mount to a UMI T/A and some other minor upgrades. Also broke my starter and had to get another

Just have to wait till next payday to get a bullet muffler and a cutout.
J

SScam68

iTrader: (20)

Cool! New Tranny is in!

I thought you had at least another week or so.

KAOS

iTrader: (5)

so adding fuel increases egts? so in order to make it spool faster ADD fuel and pull timing down low or what? i was always under the impression you took fuel out down low to help spool the turbo, i have a t74, same thing i guess, and its about the same, but i have a 1.00 AR housing. any info is great