Custard

Hi

My current setup is a bridgeport motor with a modified 0.82 A/R HKSTO4Z and I was making a conservative 430whp at 1.1Bar. Sadly that turbo didnt last too long due to a sloppy rebuild.

I'm not sure what will fit on my manifold, its HKS but not the cast unit. I was thinking a GT4094R.

I would like to make a little more power, say 450-500whp with similar spool and boost. I don't really want to go above 1.2Bar for reliability as it is a weekend race car.

Any recommendations would be a great help. Thanks

Howard Coleman

iTrader: (6)

the GT4094r is a really good turbo. i own one. it is an 80 pound turbo so that puts max rwhp on gas about 600. one of the best things about the 4094r is that is it compact unlike the 4294.

it would be a mismatch for you given your power objective.

500 would be the upper approx range for a GT35 or GTX35 as well as a BW 177272 or 177280.

you might do better w a mid size turbo that wouldn't have to be wound up so much at the 500 level. BW makes the 177283 that would be a nice fit. it has a 52 trim which promotes midrange. you might be quite happy w the .91 A/R.

howard

Custard

hi howard,

thanks.. i was quite happy with the power, spool, and boost i was running with the TO4Z when i had a stock ported motor. i recall it was in full boost at around 4250rpm, but power topped off right after 7000rpm.
Since then i changed two things:
1. I bridgeported the motor
2. When i had the TO4Z rebuilt after the hot side had blown, they changed the hot side A/R from a 1.0 to 0.82 due to either part availability or incompatibility.

when the car was dynoed and tuned the boost curve appeared similar to that of the previous setup in terms of power, spool and boost. power was slightly higher by 5%.

i was hoping to get more useable power at the top, but in my limited knowledge i think the 0.82 A/R hot sider was the limiting factor.

this is the reason for me asking about the GT4094R as i am thinking it will allow me to have useable power beyond 7000rpm.

Maybe i should stay with the TO4Z (and get a new one). will the bridgeporting result in more useable power beyond 7000rpm while staying at around 1.1 to 1.2Bar boost?

GREG

Turblown

iTrader: (12)

I don't think a GT4094R will fit the tubular HKS manifold. I would stick with the To4Z and use a 1.15 T4 turbine housing

Custard

pic of my manifold attached. anyone believe there is a concern with fitting a GT4094R?

sk8world

iTrader: (5)

I couldn't tell you if it would git or not but I used to run A gt4094r turbo and loved it! With a streetport and .96 it made good power to 8k. Made 600rwhp with it.

Went bigger so its Forsale. Chra is almost new.

Custard

thanks, if i lived in the US, i would be knocking at your door. but sadly i have to go through import agents and what not.

at what boost did you make that power?

Just for interest sake what would you ask for it. i see a new one costs about 1650USD before shipping?

BlewByYou

iTrader: (2)

Gtx35 is where its at for your power goal and spool..

Custard

Would you recommend the 1.06 A/R hot side on the GTX35R to take advantage of the bridgeport?

at what boost would 500rwhp be achieved on the GTX35R with 1.06A/R?

what about Turblown's TDX61R option?

bolo_fd

iTrader: (2)

u already have a gt35r in ur road car how much more of a difference is the gtx35? im looking for a new setup also but mines just for street and with wi.

Turblown

iTrader: (12)

He bought our TDX61R, and maxed out his old ignition system. His exact words, " So far the turbo is killer "...

Howard Coleman

iTrader: (6)

Custard

holy mismatch!

a bridgeport w a .82!

first off, there are very few situations that win overall w a bridgeport. you have huge overlap between the exhaust and intake strokes (both being in communication) so you suffer a mid range power penalty.

just as you rise out of the penalty box rpm-wise your small exhaust housing puts on the brakes.

you have the worst of two worlds.

yikes.

i am not calling you out on this, just identifying your situation for you.

you want 450/500 hp but you also want to run only 1.2 bar (17.4 psi). 500 generally takes just above 20 psi.

if you want to limit to 1.2 bar i do suggest something similar to the GT35.

if you want closer to 500 and will run 20 psi then you need the mid size turbo such as your TO4Z w a 1.0 back end. or the BW 177283.

the GT4094r is a great turbo but does not fit your needs.

either the GT35 or BW will fit your manifold. you may have to adjust your downpipe.

so it is your call... if you have a genuine HKS TO4Z and it is in excellent condition i would just swap in a different hot housing and get back on the track.

i am wondering what is going on w the 7000 rpm thing though. even stock port motors run past 7000.

howard

Custard

Thanks for the feedback howard, i agree with you fully, the 0.82 was a waste of time and money. bought the 1.06 TDX61R from Elliot at turblown and slotted it in. with the current setup the car made between 373 and 397wkw at 1.5Bar boost at just over 6000 rpm (2 seperate runs). beyond 6000 rpm the ignition and fuel was apparently a problem, so this is being sorted. also found that the timing was a too agressive and that this needs to be looked at for reliability.

at these power levels do you recommend water injection? im using AVGAS (100LL).

thanks

GREG

Custard

Dyno chart attached.

bolo_fd

iTrader: (2)

How much does the tdx61 flow compared to a gtx35? I'm looking to get a new turbo for my street ported engine and have similar goals as Greg. Going to add mech wi too.

Turblown

iTrader: (12)

I haven't paid for a compressor map to be generated, but back to back dynos( GTX35R VS GT35R with one of our TDX wheels) made roughly 10 more rwhp. Same car, same tune, same day, within 20 minutes of each other.

This is only half of the picture as our TDX61R uses a 74mm turbine wheel vs the GT35R's 68mm turbine wheel. Our TDX61R makes roughly 70+more rwhp @ high boost over the GT35R. Back pressure and EGTs are also lower too, engine and turbo reliability is better, not to mention a GTX35R is roughly $600 more expensive.