New to turbos and have a few questions.

[Swiggart]

Alright, im starting a turbo build on my auto lt1 powered rx7. I want to run somewhere between 6-11 psi of intercooled air. Right now my car is on nitrous, and I have a 230/236 duration 544/554 lift @ 110 lsa cam and some decent port work on my heads. I have a 2800 stall as well. I mostly need help on turbo size, I want the power to be better on the top end than on the bottom end since my car already has a hard time getting traction. What would be the best size/and spec for my build? It is a front mount set up.

[Fastbird]

PT76GTS turbo from Precision, which I believe is not referred to as the PT7675. It's got a .96 A/R housing, 4" inlet, 76mm inducer, 3" exhaust outlet, 3" turbine outlet. Pretty much the biggest T4 flange turbo you can put. T6 flange turbos are typically a LOT larger and you really have to start making sacrifices to fit them on the car.

On your build, I would NOT run that cam though. Way too much overlap. Look for a wider LSA and the least amount of overlap you can get. If the engine is internally stock, don't plan to run more than 6 or 7 lbs of boost unless you want it to live a short life.



*edit* Look at that, I hit 10,000 posts like 10 years after Larry. :D

[popo8]

lol

LTXtech.com is my drug.

[96lt1m6]

First issue to address is your NON-Boost friendly camshaft... give these links some attention they have great content.

http://ls1tech.com/forums/forced-induction/208864-turbo-faq.html
http://www.forcedinductions.com/help.htm

[Ryan Stout]

I actuslly bought a new cam last night, old one will be FS as soon as I pull it.

LE turbo cam. Made power up to 6500ish.
224*/224* @ .050
.575"/.575"
114ls

Like fastbird said, you want a lot less overlap.

Listen to fastbird, he's a smart guy.

Sent from my SCH-I535 using Tapatalk

[Fastbird]

I actuslly bought a new cam last night, old one will be FS as soon as I pull it.

LE turbo cam. Made power up to 6500ish.
224*/224* @ .050
.575"/.575"
114ls

Like fastbird said, you want a lot less overlap.

Listen to fastbird, he's a smart guy.

Sent from my SCH-I535 using Tapatalk

Ryan that cam is strikingly similar to the turbo cam Ben bought me from Lloyd last year. What are you putting into the car in it's place?

[SWells]

Not exactly what you are looking for, but I found this site educational.

http://www.junkyardturbos.com/Rear-Mount-Turbo.php

[MI6TA]

That was a very informational writeup SWells thanks.

[Ryan Stout]

Fastbird its a cam motion cam my buddy ran last year. 240/237 600/600 114 iirc. Or similar at least. Have to double check the card.

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[GuillaumeC]

Like fastbird said, you want the best flowing turbine if high RPM power is what you want.
A T6 would be ideal, but they are huge... here's what a T6 looks like:

http://i121.photobucket.com/albums/o210/mtl9c1/project/2014-02-09112211.jpg

If you can find the room that would be your best bet, but the 0.96AR T4 is probably a better option because of the size.

[shownomercy]

A T6 turbo and a light weight car seems like a horrible idea to me for a car that wants to be a decent daily driver.

I have the same turbo as fastbird, and its great, snappy response around the town and it does pretty well for a "tiny T4 flange" unit.

[Swiggart]

Wow, thanks for all the help guys. I will definitely be looking for a good high rpm turbo cam as well as a big t4 flange turbo. Also another thing I am confused about is thd maf sensor. What are people doing with them? I was thinking putting it inline with the cold piping to the intake, but I need some insight. Also, is there a good way to get oil lines ran from the lt1? Seriously, thanks for all of the help and input!

[blkchevyz]

maf is going to be up to the tuner. some like to do a speed density tune and eliminate it.

regarding oil, you can get pressure from the fitting above the filter. return you can tap the pan and drain it back in that way, or if you are running a remote setup and already have a pump you can just run it into the valve cover.

[GuillaumeC]

I get the oil from the oil pressure port on the top of the block right behind the intake manifold and it drains back on a fitting I welded on the oil pan on each side.

Most people running boost and big HP do not have a MAF, it's tuned in SD.

[Fastbird]

If you stick with the MAF, get it as close to the TB as you can (stock location area). Reason for this is if you blow charge pipes apart at the couplers or develop some other cold side air leak, it won't register as a vacuum leak and make fueling go wacky. MAF close to the TB, Blow Off Valve Between Turbo and MAF.

[shownomercy]

Biggest T4 turbo will be something like an older PT88 or the newer 8847 which is a PT88 housing with a new cartridge (GT4788 assembly).

The PT8847 is the unit I will be getting once I max out the 7675 I have.

[Fastbird]

Ooh.....an 88 on a T4 flange? Yummy. Just wish we could get a bigger a/r on the T4 stuff.

[shownomercy]

Ooh.....an 88 on a T4 flange? Yummy. Just wish we could get a bigger a/r on the T4 stuff.

Yea, still limited to the .96ar but you get a better compressor wheel.

The new version is a 2200 turbo... so, dealing with a baby T4 7675 or similar would make much more sense, otherwise, jump to a entry level T6, S480 etc

[Swiggart]

Hey man, see you have an rx7 similar to mine. Just curious what your car is running for times and traps. Also, I get pressure from the block and then send it back to the pan, would I be able to run it to the valve cover or would that cause problems?

[shownomercy]

Hey man, see you have an rx7 similar to mine. Just curious what your car is running for times and traps. Also, I get pressure from the block and then send it back to the pan, would I be able to run it to the valve cover or would that cause problems?

If your turbo is higher than a valve cover or you have a scavenge pump you can put oil there. Otherwise, drain needs to be lower than turbo, which normally means pan.

[GuillaumeC]

Hey man, see you have an rx7 similar to mine. Just curious what your car is running for times and traps.

It's really not that fast right now, mainly due to the exhaust that's choking the motor... it has a nice NA stroker but the headers are 1.5" primaries into dual 2.25" exhaust then into a single 3" pipe to the back.
It ran 12.0 @ 117 mph in the summer heat.


Also, I get pressure from the block and then send it back to the pan, would I be able to run it to the valve cover or would that cause problems?

A turbo drains by gravity, so the drain line has to go towards the ground without going up.
If you want to drain into the valve cover you'll need a scavenge pump. They are popular in applications where the turbos are mounted low.

[Swiggart]

It's really not that fast right now, mainly due to the exhaust that's choking the motor... it has a nice NA stroker but the headers are 1.5" primaries into dual 2.25" exhaust then into a single 3" pipe to the back.
It ran 12.0 @ 117 mph in the summer heat.



A turbo drains by gravity, so the drain line has to go towards the ground without going up.
If you want to drain into the valve cover you'll need a scavenge pump. They are popular in applications where the turbos are mounted low.

Okay, so I use the pressure from the block to the turbo, then I need the drain to be lower than the turbo if I dont want a scavenge pump. I will get a nice list of parts I need and post it up here and see what i am missing. Thanks alot everyone. I will be needing more help probably sooner than later but all of your opinions are appreciated!

[Swiggart]

It's really not that fast right now, mainly due to the exhaust that's choking the motor... it has a nice NA stroker but the headers are 1.5" primaries into dual 2.25" exhaust then into a single 3" pipe to the back.
It ran 12.0 @ 117 mph in the summer heat.



A turbo drains by gravity, so the drain line has to go towards the ground without going up.
If you want to drain into the valve cover you'll need a scavenge pump. They are popular in applications where the turbos are mounted low.


A T6 turbo and a light weight car seems like a horrible idea to me for a car that wants to be a decent daily driver.

I have the same turbo as fastbird, and its great, snappy response around the town and it does pretty well for a "tiny T4 flange" unit.

Is a 10.0 compression motor too much? I want to go with a t76 .96 ar turbo, intercooler, and have the engine how it is other than change to a turbo cam. How much boost could I run on 93 octane fuel, with the setup above? The engine only has a few hundred miles, but my auto teacher with a few turbo sbc'sis wanting will help build it so I want to do the turbo setup now. I think the 10.0 compression with a turbo cam and 93 octane should be sufficient to run boost, but how much?

[ZOHAN]

Where are you getting 93 around here? 10.0 isnt bad as long as the tuning is good. Few hundred miles on a stock rebuild? If its stock crank, rods, pistons id only do 6-7. Could you do more, yes... but even at 6-7 it could last 10,000 miles, or 100...

Making you silky smooth...

[Swiggart]

It's really not that fast right now, mainly due to the exhaust that's choking the motor... it has a nice NA stroker but the headers are 1.5" primaries into dual 2.25" exhaust then into a single 3" pipe to the back.
It ran 12.0 @ 117 mph in the summer heat.



A turbo drains by gravity, so the drain line has to go towards the ground without going up.
If you want to drain into the valve cover you'll need a scavenge pump. They are popular in applications where the turbos are mounted low.


Where are you getting 93 around here? 10.0 isnt bad as long as the tuning is good. Few hundred miles on a stock rebuild? If its stock crank, rods, pistons id only do 6-7. Could you do more, yes... but even at 6-7 it could last 10,000 miles, or 100...

Making you silky smooth...

There is no 93 that I know of, but I have found by doing some researching that you can mix toluene in with 91 and get 93 with a 15-20% of toluene. It has forged crank, x rods, and high quality cast pistons (better than average). I plan to get a base tune through mail and then dyno tune at a shop my girlfriends dad is friends with. This is a long term build but it should be up and going be for summers over.

[GuillaumeC]

With a good tune it should be OK as long as you dont go crazy with the boost and timing advance.
Forget the gasoline additive, get water/meth injection instead. :)