Think I bought too small of a turbo.

[1fstss]

So I got my 7875 turbonetics and it's significantly smaller than my f1a... I figured the 78 might be close but it's notice my smaller. I was told to get a 88 but I thought that may be too big.. Now I'm having regrets! Is this just an optical illusion? Or am I going to lose power going to this 78?

[Fastbird]

Physical size is one thing. Terminal impeller speed is another. You can utilize that 7875 more than the F1A. Biggest drawback is if you reach a choke point because of the smallish A/R on the impeller side of the turbo. But it'll take a LOT of expelled gasses to do that.

Posted from my LG G2

[shownomercy]

The turbine side will kill you but that is the price we pay for mid frame T4 units, make sure you have a free flowing exhaust or cutout in the downpipe.

Otherwise, it will be a great turbo. Mine is only a 7675 and it does make some steam.

[GuillaumeC]

So I got my 7875 turbonetics and it's significantly smaller than my f1a... I figured the 78 might be close but it's notice my smaller. I was told to get a 88 but I thought that may be too big.. Now I'm having regrets! Is this just an optical illusion? Or am I going to lose power going to this 78?

How much power do you want and how high are you planning to spin the motor?

[1fstss]

I'd like to keep it around 800rwhp. And revving to 6800.

[shownomercy]

I'd like to keep it around 800rwhp. And revving to 6800.

Better have a very good meth system and a open downpipe. You will be pushing it hard.

[GuillaumeC]

0.96AR T4 turbine?

383ci @ 6800 RPM will probably choke on that turbine. :(


FWIW I'll be spinning my 357ci too 7000 RPM and I have a 1.23 AR T6 with a 93mm turbine wheel. While mine might be on the "big" side of things, your T4 will definitely be the bottle neck in your turbo setup.
It will make 800whp, it's the 6800 RPM with a 383 that I'm pretty sure will be a problem.

As was said before, you'll need all the exhaust flow you can get... big DP, cut-out, etc.

[1fstss]

Car will have a meth kit but I figured the ad was a bit small... Was just hoping I could close my eyes and wish :)

[shownomercy]

Car will have a meth kit but I figured the ad was a bit small... Was just hoping I could close my eyes and wish :)

http://ltxtech.com/forums/showthread.php?26364-help-me-spec-a-turbo!!/page3

It will be fine, you can always swap it out later for a PT8847. You are putting the cart before the horse here. Build it, dyno it, race it.

Then evaluate. 800whp through a non locking auto is a shit ton of power fwhp wise. I personally think you are overstepping but, thats me.

[1fstss]

The car made 601 on a 8:1 350 on the f1a. It made 430 at 4k with no tuning on the stroker before it pooped the balancer. Like it had 0 timing advance. Our best guess was it would make 700 and change with timing advance and some fuel tuning once the procharger spun up.

[MoeHorsePower]

The car made 601 on a 8:1 350 on the f1a. It made 430 at 4k with no tuning on the stroker before it pooped the balancer. Like it had 0 timing advance. Our best guess was it would make 700 and change with timing advance and some fuel tuning once the procharger spun up.

601 at what RPM, no tuning? on a NA tune? and what do you mean 0 advance. I made 722 RWHP on a D1 so????

[1fstss]

6300 rpm not a NA tune, speed density tune. When I say 0 advance means we turned the timing to 0 in the tune. I was over powering the twin intercoolers. So with any timing I was getting spark knock. And congrats on your number.

[shownomercy]

I only made 537whp :(

[MoeHorsePower]

6300 rpm not a NA tune, speed density tune. When I say 0 advance means we turned the timing to 0 in the tune. I was over powering the twin intercoolers. So with any timing I was getting spark knock. And congrats on your number.


How much boost are you running?

[MoeHorsePower]

And honestly, the 722 rwhp was on a ragged edge tune with some high octane fuel, on a safe tune it only made 648 RWHP

[1fstss]

4 in pulley I was making 18-19 psi. But I never got a clean run with it. Last time at the dyno the harmonic balencer split and came off lol. I had bad luck with the procharger so I sold it and am going to that 7875.

[MoeHorsePower]

4 in pulley I was making 18-19 psi. But I never got a clean run with it. Last time at the dyno the harmonic balencer split and came off lol. I had bad luck with the procharger so I sold it and am going to that 7875.


OK, I dont understand the overpowering of the intercoolers..with that boost you should still have a min of 10-13 degrees of timing

[shownomercy]

Bad luck with something that literally bolts on, but you want to try a complete custom turbo kit....?

How old are you again?

[1fstss]

Well... The procharger ate it's self once... One of 3 known to have the nose cone fall off and suck into the blower. Procharger fixed it with some convincing. After that I had a bearing failure with like 20 miles on it full of oil. I had a close friend rebuild it this time after I sourced the bearings. And I'm 33... Been fighting it for about 5 years. Although it seems to be all good now I just want a better power curve. And the tuner changed the timing advance to 0 even from factory. Although now it could be turned up.. I don't know if the twins had a blockage or what but they where a restriction. And installing a turbo isn't rocket science. The only custom part is me standing up the radiator. Also... Installing a f1 a isn't just a bolt up thing... I had to massage the block to clear the blower. And you have to delete or modify your abs unit so it doesn't hit the compressor. Thru all the bad luck I loved the procharger. But a turbo simply makes a better, more usable power curve.

[dawdaw]

Don I think you just need to bolt this turbo on.. make sure everything is mechanically sound, and don't screw around and take it to Baker engineering and have them tune it... tj is tuning one of the fastest outlaw turbo drag radial cars in the nation and knows his shit... I have no clue on turbo ar, compressor wheels, etc but from looking at others builds I think you should have no problems putting 600 down threw a stalled auto Some high dollar race gas and aggressive timing Even more but run this one till it runs out of steam then do some research on what would be an upgrade. . The pt88, s480, on a t4 flange.. but I definitely wouldn't worry about the turbo you have now. Snm how comparable is his turbo to your's? Pretty darn close aren't they?

[1fstss]

Tj is the person who has been tuning the car ;). And I've always wanted to go turbo anyway. The SS I want on pump gas... The z28 is the go fast car :)

[dawdaw]

Well get it going on then old man :)

[1fstss]

I drop the procharger off the 26th and get the other half of the money. Then I get to pay for the hot side :)

[shownomercy]

He has a 7875, which means a 2mm bigger impeller and same size turbine as me. I have a Precision, his is a turbonetics or whatever.

Should be very close performing, hence my somewhat annoyance at asking repeatedly about the thing. I have no doubt mine will take me to a gear limited 143 trap, with pretty awesome transient response on the street. What more can you ask from a little mid frame T4?

want big ass stupid supra dyno numbers, get a 88mm and a T56. Otherwise, get it done and race it.

[GuillaumeC]

Should be very close performing, hence my somewhat annoyance at asking repeatedly about the thing. I have no doubt mine will take me to a gear limited 143 trap, with pretty awesome transient response on the street. What more can you ask from a little mid frame T4?

Just curious, how many cubes do you have and how high are you spinning it?

[1fstss]

Just a nasty habit of second guessing myself. And if you don't ask you'll never know :)

[shownomercy]

Just curious, how many cubes do you have and how high are you spinning it?

383ci, 6400 shift