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Spooling a big turbo./ lots of grip

MJTru

By MJTru,
in Engines & Forced Induction

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MJTru

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Well today I tried a new setup on one of my r32 gtr build I had done a while ago. When I say tried it. I mean race the car.

This car makes good power once I'm off.

It had tons of grip and I can't seem to get it going off the line even if I pin the gas to the floor at 8500 rpms. It's a built motor but uses a old gst72 turbo. It's a old turbo long with that being a journal bearing.

What I'm doing it comparing it to a smaller set I had on another one of my car. I trying to find out what could be the problem if not it being the turbo itself.

I'm guessing the turbo is a 72mm.

For now I know my breaking gearboxes

In 3rd with this car and until my os88 is delivered in have no choice but to use the 3 stock boxes to work things out. Oh

I have 2 r33 box that I'm going to be keeping for gear sets. Just to try out.

Anyways what's happening to the car is its bogging off the line no matter how hard I let it go in first gear. I guessing the grip is alot more than my other cars and it sitting on 4 275 tires nto1's. I'm guessing it's the turbo. Being a journal bearing and a old design. Or is it the cams as this car is my first car using cams. That's one concussion I can come up with, as to the difference between the 2 cars. One was full stock. And this one is built, but so much more lazy off the line. After I smashed 3rd gear I gave it my best to see what it would take to smash 1st and even second gear. But the car would just fall over on itself and bog off the line. It goes it just like my other gts4. I'm wondering what all could be my problem here.

What's the biggest turbo I can run until it would act this way. Is it because it's big and a journal bearing turbo. Is my cams affecting the tune down low and what could I look for/or do as evidence of this.

I'm stumped here. I'm sure I have no boost leaks, but worth checked. Is my turbo oversized. One solution is to use an anti lag device off the line, but it's so hard on the motor and the turbo.

 

Any suggestions would be appreciated guys.

 

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MJTru Mentor

MJTru

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Yeah I'm stumped to. It has to be timing and fuel I was thinking the same thing. On launch I don't see to much black smoke indicating fuel. I'll also check the timing.
It has to if it's to advance I can see it not reaching peak cylinder pressure and killing my take off. Also to lean to be bad. But I don't feel it a lean problem. Best to start logging this week end. I need to buy to damn hub dynos.
Thanks for ideas guys

baron_von_bootsector Enthusiast

baron_von_bootsector

Posted
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The turbo is a bit archaic but it could be that you just are not able to get enough load to get the turbo up on steam?

I completely agree with Allan on putting a built auto and transbrake into it - would make launches so much easier / consistent and will put a stop to your exploding gearbox dramas. Going with a more modern turbo and potentially changing cams / timing would likely help if you want to remain torque-converterless.

Anti-lag would help the situation but you are right it can be hard on the hot side depending on how you do it - what kind of ECU are you using?  

MJTru Mentor

MJTru

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Thanks guys. I have already paid for a OS88. So the power glide is out, but may be a solution for another build. After I slowed down and looked at things I'm not sure but I'm thinking it's timing because of the 272 cams in the motor. As it should rip the tires up like mentioned above. At 22psi and 8500 rpms it shouldn't fall flat on its face then go. It bogs all the way down to like 4k.

Then gradually climb up and as boost kicks in at 5500 pulls hard after that.

Between the motors only the cam is what's different. As the duration is way more. I'm thinking of what I'll need to do to get her going timing wise. As the cams are leaving valves open longer and a small bit more lift. I should slowly start to retard the timing whiles looking at my knock levels and making sure there is adequate fuel. Hmmmm cams are hks 272

 

Whats the cost for full power glide setup. ???

 

 

 

MJTru Mentor

MJTru

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8500rpm launch and its bogging is abit strange to me 
should be blazing tyres once ur off the clutch
sorry don't know what it could be

I have ever had this same motor/cam in another body and it was the same thing. Couldn't launch. I'm thinking it's the cams. Hks 272. I'm not sure of the lift. May be standard. But the added duration I feel may be my problem.

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