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Road race turbo

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Old 11-19-18, 07:41 AM
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Road race turbo

Hi all, getting back into the track game after a long layoff. I have a dedicated FD track car with a big *** laggy turbo, hits super hard and good for a high speed track like Watkins glen but costs so much time exiting corners or trying to modulate throttle roatating the car. 2011 was last time on track. For the guys who race what is a good fast spooling reliable turbo set up? I’m looking for 400/ 450 rwhp, have big inter cooler, duel oil coolers etc..thanks for any info
Jim
Old 11-19-18, 01:11 PM
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To swap to a new EFR turbo it will be $2k+

To swap to a new SXE unit will be close $1k

To swap to a 4.44 or 4.7 ring and pinion so you exit the corners above 4,000 RPM and in boost will only cost you a few hundred.


Do the math and look up the MPH by gear with a 4.44 or 4.77, does that mesh well with your tracks? Are you doing 150 MPH at WGI?
Old 11-19-18, 03:33 PM
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If you have the funds and want to make a solid improvement to your car I would do both the 4.77 rear and the EFR 8374 turbo with re-tune.

On my street/autox/hillclimb/kart track RX-7 I went from T04B 60-1 I had used for 14 years to the exact same size compressor EFR 7670 and the difference in the character of the car/engine/driveability was incredible.

The rotary exhaust seems to make a huge difference on these lightweight exhaust wheel (Titanium Aluminide) EFR turbos.

Like you say, with the "laggy" (full boost by 3,400rpm) 60-1 I had to floor it and ease off the gas just the right amount as the wastegate cracked and/or counter steer just the right amount as the wastegate cracked to keep on line.

With the EFR I could just tip in the throttle progressively and feed the near instant torque in. You know how much torque you are getting as you feed it in so its much easier to judge.

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Old 11-19-18, 06:46 PM
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Thanks guys, I will look into it.. 140 ish into bus stop at the glen, no downforce for the esses. Had a chance to time trial at Monticello before they closed it to average folks and was 150 plus on the long back straight there and it was still pulling..funny how noisy it is at that speed and all the dirt particles etc that get dislodged and float around the car!
Old 11-20-18, 11:47 AM
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Not thing laggy with big port and stock style twin, even with 4.777 I run at my last endurance race ,
With shorter gear, I am loose some lap time at corner like I can hit rev limit in 3th, now i have to shift to 4th, this loose some time when u still using syncro box
I am in market for single turbo too , I am think EFR too
Attached Thumbnails Road race turbo-a88a2859.jpg  

Last edited by diyman25; 11-20-18 at 11:48 PM.
Old 11-23-18, 02:13 PM
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If you're not chasing giant dyno queen or drag numbers I really don't think an EFR can be beaten if you've got the scratch.
Old 11-25-18, 08:02 PM
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Hi Jim,

As a comparison to what others have mentioned, I run a Precision 6262 on my track only FD. Prior to the Precision, I was running an Aspec 3574 and the Precision seems very similar. See the attached dyno pull below, I think this was at 18 or 18.5 psi.

Guy


Old 11-26-18, 11:09 PM
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I had good luck with a garret gt35r with a 1.06 housing.
Old 11-28-18, 10:03 PM
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Originally Posted by finger lock
Hi Jim,

As a comparison to what others have mentioned, I run a Precision 6262 on my track only FD. Prior to the Precision, I was running an Aspec 3574 and the Precision seems very similar. See the attached dyno pull below, I think this was at 18 or 18.5 psi.

Guy


Thanks Guy, good numbers. How is the feel of your car with this turbo? Is the power linear. Not sure if you ever raced a 2 stroke dirt bike but my power is like that..not a lot..then hang on..I’m about 18 psi but I have to stay so busy trying to max out the car it’s crazy..I even started messing around with a little left foot braking and feeding some more rpm trying to keep the turbo spooled..if I had a foot camera it would look ridiculous what I’m doing to try and achieve a fast lap.
it is fun driving a high hp car with a short wheelbase and no abs or any other computer aid..when I first started in the mid 90s all the cars were like this but now I feel like a novelty using heel/toe..getting ham fisted on the brakes will cost me a grand in flat spotted tires..
some of the guys with the modern paddle ****,traction control, abs cars would put our cars in the fence trying to run them at the limit in my opinion 🙂
Old 11-29-18, 01:56 AM
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Jim,

Yes, the response is mostly linear and quite responsive. It makes for a good package.
I would also listen to Racingdriver, he has lots more turbo track time than I do.

Guy
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