cajundragger

iTrader: (2)

Gents,

Looking to start a conversation about a pair of 58-61mm turbos.

Target engine is LS3/L92, stock heads/block(bore)/crank. Forged rods, pistons, turbo cam, valve train to suit.

Car is sub 4k pounds, T56, 3.73 gear, street car. I emphasize street.

Power goals are sub 1000chp, say 7-800whp. 8k redline. Pump gas, no corn. no meth/nitrous. A2W intercooler, mounted in holley intake.

Hoping to do optima street car shootout(think autox), road courses, some standing mile, 1/4 mile here and there. Real jack of all trades, master of none deal.

Based on my lower(by most of ls1tech's) power goals- I don't see the need for twin 62mm+ turbos. I'm looking for efficiency to keep temps down as pump gas is a must.

I understand horsepower is a game of flow. My thought was the smaller T4 turbos would fit the bill. GT35s, PT5858, ON3 61?, etc Will something like these work without detonation issues? Would I need more displacement for less boost pressure? Ported heads?

Is ball bearing much more noticeable? A bunch of formula drift guys run the GT35rs with ball bearings- but I am sure they are also sponsored. Not looking to build it cheap or sloppy- but if a pair of $600 turbos will perform just as well as a pair of $1600 turbos- it would be helpful to know.

What are you guys thoughts? I know this is a little different than typical questions on here.

TIA

Orr89rocz

iTrader: (13)

.68 or so ar turbine 61's would be fantastic. I used to run that combo on a 400" sbc low rpm deal. Make instant boost and huge torque. Was hard to hook up lol

I think you are on target with your goals. Should only take low boost to get 700 whp in a cammed Ls3 head deal.
Air to water is effective but not sure of holleys setup. How large of a reservoir? Will there be an exchanger? Sustained boost racing i would have a decent sized water tank and possibly an exchanger mounted up front.

cajundragger

iTrader: (2)

excellent. I am looking for experience. If anyone has any dyno charts or similar they want to share I am all ears. Turbo selection is the roughest part- too many options. I'm trying to look at over the counter twin kits- but most are much larger than I want. There isn't a ton of information on smaller TT builds.

I could probably build much more HP for same dollar, but that isn't the point. I'd never put it to the ground and I will eat T56s as fast as I can install them.


A2W intercooler much like 'crusty nova' has used. I'm sure it will take some R&D to figure out but it has very short intake tubing and tight packaging.

http://cdn.speednik.com/files/2015/06/nova-1.jpg


I'm building basically a copy to this car but not oriented to only light street/drag. I want a much broader 'use'- although I am prepared to not be great at anything.

stevieturbo

AGP Turbo basically do exactly what you want with their Gen5 kits.

And staying effiicient isnt achieved with baby turbos, it's the baby turbos that create heat by needing to work harder.

cajundragger

iTrader: (2)

AGP looks to be using a 55/57 turbo with .63 ar for their fast spool 800whp kit.

I think I am right on target with my initial guesses.

By efficient- I meant stay within the map of the turbo. Turbo size doesn't play into efficiency- small turbos can be efficient if you run them within their map. right??

stevieturbo

Yes, but by nature of them being small, and asking more power than is realistic...they wont be running within the efficient ranges of their maps.

it's a trade off, if you want fast spool go small and accept the hotter air and deal with it.

If you want more efficient and more power go bigger, and accept the spool tradeoff.

It's up to you to find that balance, but 800hp is a pretty moderate goal and even smallish turbos should be perfectly fine
Give AGP a call, they certainly seem to have tons of experience, and even more turbo options !

cajundragger

iTrader: (2)

really stupid question- but are turbos marketed off of their compressor or turbine size? such as a '62mm' turbo. is that compressor or turbine?

I imagine I want to stay within the T4 frame. Most reading I am doing says the T3 is just too small.

I don't want power to fall off sharply, but I will give up a few peak for a fatter midrange.

garrett has so many turbo options it is unbelievable.

cajundragger

iTrader: (2)

Looks like AGP is running the entry level Precisions. I wonder the difference between the 55/57 entry and the 55/58race. price is ~300 difference, but HP level is 520 compared to 590.

http://www.agpturbo.com/precision-5531-mfs/

stevieturbo

They're marketed of both, there are just a shitload of options.

Most T3 housings are small, but some places do make them now with much larger A/R's to accommodate more flow/power on a smaller frame unit

So it isnt as easy just to say they are too small, as there are loads of variables.

mkvamso

iTrader: (2)

I used cxracing gt35s, started spooling around 2800 and were at full boost a few hundred rpm later
Carried well to 7k plus and made mid 700s through an unlocked auto

cajundragger

iTrader: (2)

was this the 5.3 in your sig?

I'm slightly concerned about running another liter of displacement through them plus another 1000 rpm. The cxracing and ON3 turbos do look sweet from a price perspective- and you can't deny they work well.

I've always been told the knockoffs are yesterdays tech though, and create havoc on IATs and backpressure. But if I purchase something like the entry level turbos from precision- how much technology is different between those and the knockoffs?

I need to call AGP and speak with them. Will do that early next week.

On to the topic of detonation- how much boost pressure before meth or corn is required? This is my biggest concern. I know IAT plays a big role, and overall timing. I'm fine leaving a few degrees of advance on the table but I do not want secondary systems to make the power. I don't have corn around where I live- and also I want to be able to get in the car and go anywhere- and not worry about finding fuel.

DavidBoren

Running a turbo off its island plays havoc with your iat's, not old technology. And incorrectly sized exhaust housings cause backpressure issues. Once again, not old technology.

I would get bigger (~70mm) exhaust housings to help reduce backpressure, with low-ish ar's (~.6x) to help them spool.

For sustained boost runs, like a long road course or standing mile sprint, I would definitely want a large reservoir for your a2w intercooler. If your car still has the a/c system, I would hook the intercooler to the a/c via a Forced Induction's active intercooler custom kit, as well as use a large reservoir.

jmm98LS1

iTrader: (28)

I run a pair of turbonetics 61/65s on a 370" with a t56. Start making positive pressure at 2800rpm and are at full song soon after. Makes 663/661 on 11psi and made 890/813 on 18psi spinning hard on the dyno. It's silly fun on the street!

cajundragger

iTrader: (2)

would you be interested in sharing your dyno chart?

spraying meth or running corn?

have a build thread?

jmm98LS1

iTrader: (28)

Never made a build thread. I'm running E85 (tests at 70%). Here's the chart....brown line is 11psi and 17* timing. Green line is 18psi and 17* timing. Red line is 18psi and 18* timing, and that's where I started fighting traction on the dyno so stopped there. I have .68 exhaust housings and think I'm starting to max them out, it falls off pretty hard at 6500 on higher boost.

cajundragger

iTrader: (2)

excellent- do you have what series turbos you are using?

Its so confusing with so many options.

stevieturbo

If it's falling off at 6500, I'd say that's more down to camshaft than turbines, unless you're seeing insane levels of backpressure.

jmm98LS1

iTrader: (28)

They are just the $750 T series with cast wheel, bought from Huron speed.


You can see in the lower boost pull it does not fall off like it does at higher boost, so the cam still makes power up there. BTR spec'd the cam/springs to pull to 7k rpm. Jon at Huron told me when I ordered the turbos that the .68 housings may need changed out to .81 to make power up to 7k.

cajundragger

iTrader: (2)

this sounds sort of retarded but hear me out...

What about twin gt37va-

compressor: 62mm inducer/88mm exducer .58 a/r
turbine: 72.5mm inducer/66mm exducer ~.4-.9 a/r

These turbos are stock on duramax and powerstroke diesels. They are watercooled so temperatures can be maintained.

the compressor seems very well sized and flows about 4-500hp. They really aren't much different in specs that the 61/65 turbonetics, except they are variable vane. Different years have different turbine housing sizes- I'll need to do more research- but this seems like a sweet turbo to build boost early and flow well up to 8k rpm.

I understand controlling the variable vane could be a PITA for some- but I see it as a challenge. I'm handy with electronics so I am sure I can build a tune-able controller for it.

Thoughts?

slowride

iTrader: (3)

Diesel turbos are fine for the most part, but I doubt the VGT part would last at the higher gas EGT's. They would probably bind up and not move or stick, etc.