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Turbo 3.1L lack of power


djz

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We gave it a run with only 1 of the rear mufflers connected, it was pretty loud hopefully it'll quiet down a bit once the other one is connected. Might have to add a resonator in the middle as well.

 

Yeah I know there is a stud missing out of the turbo flange, the rear pipe is quite low and the tips aren't attached yet.

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Long story but I haven't driven it yet, I sat in the passengers seat while my flatmate drove it, seems to come on boost a bit quicker and it definitely felt gruntier. I'll take it for a drive tomorrow night once I've got the missing stud sorted.

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I've been a big fan of the twin muffler setup since the early 80s when I ran them on RX-2s.

 

Good too see you didn't have to angle them over because of height issues.

 

I'll probably be going this route on my M30 since I want to run 2 chamber mufflers to keep the noise down but still get decent flow........plus......I like the look.

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Took it for a quick drive before, it's definitely too loud I'm going to see how much it quietens down with the 2nd muffler connected but I'm pretty sure it's going to need a resonator. Sounds really nice as it is, but yeah just too loud.

 

Seems to have boost problems now which I'll have to have a look at sometime, I'm using an HKS EVC3 which I may have to "relearn". It runs fine and boosts 0.7 bar perfectly, pulls a lot harder than it used to but when the boost is turned up to 1.0 bar it gets up to 4500 - 5500 rpm and all of a sudden loses power and makes a really loud backfire/frontfire - I think it's spooling a lot faster than before and the EVC is confused and is slamming the wastegate open early?

 

I'll try and get the exhaust finished and boost control sorted this weekend and put it back on the dyno the weekend after.

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Took it for another drive, still backfiring when set at 1.0 bar, it appears it making 0.96+ bar when set at 0.7 so yeah, it needs to be relearned. Feels a lot more grunty off boost as well which is good.

 

Yup Soichi will be tuning it again if he can fit it in, he used to own one :)

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Took it for another drive, still backfiring when set at 1.0 bar, it appears it making 0.96+ bar when set at 0.7 so yeah, it needs to be relearned. Feels a lot more grunty off boost as well which is good.

 

Yup Soichi will be tuning it again if he can fit it in, he used to own one :)

 

He used to own one.... Intresting.. Might be a good place to go to get mine tunned in the end.. What did that cost ?

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His normal charge is $150 (the same as HiTech Performance) just for a couple of runs with no tuning, he spent probably about an hour playing with the tuning and charged me $225 all up which I thought was pretty good.

 

What computer will you be running on your car? How's it all going anyway? Pretty close to being able to be started?

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His normal charge is $150 (the same as HiTech Performance) just for a couple of runs with no tuning, he spent probably about an hour playing with the tuning and charged me $225 all up which I thought was pretty good.

 

What computer will you be running on your car? How's it all going anyway? Pretty close to being able to be started?

 

Im miles away yet... :( Money doesnt help.. Most of the body work is done. Just a few little touch ups and blending before it gets painted.. As that pic shows. motor is in..

 

Im looking at using a link G4.....

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  • 2 weeks later...

Exhaust is all done - finally. Added a resonator in the middle and moved the flexi further forward, still louder than I would like but not too much I can do about it. We bent up a wastegate pipe at work and put that on too, it's kind of funny driving it on boost now, the wastegate makes no noise at all - bit of a change since it hasn't had a pipe on it since being turboed.

 

The backfiring problem seems to be fixed, we relearnt the boost controller today (bit naughty, you have to do 2 runs to the redline in 3rd gear which works out at about 160ks) and it's behaving now, very steady at 0.7 bar. It may have been pinging slightly on 1 bar. I'll have to try and get it back on the dyno next weekend.

 

I'm still worried about the cam timing, I really need to get an adjustable pulley. I changed the cam pulley from position 1 to position 3 after dynoing it last time and I think it gained power, I changed it back to position 1 last weekend. I have to play with it a bit more.

 

Any other advice before it goes back on the dyno would be much appreciated.

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  • 1 month later...

I have to apologise to whoever I told that I couldn't put a bigger throttle body on the standard manifold, it was actually pretty easy. So I've now got a 62mm throttle body, a more ported inlet manifold and a cable throttle.

 

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But after all of that and the 3" exhaust I'm now making 226.7kw (304hp), a gain of 15ish hp, not quite what I was expecting.

 

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Any other ideas guys? Should I go back to a standard head and cam?

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I have to apologise to whoever I told that I couldn't put a bigger throttle body on the standard manifold, it was actually pretty easy. So I've now got a 62mm throttle body, a more ported inlet manifold and a cable throttle.

 

CIMG67232.jpg

 

But after all of that and the 3" exhaust I'm now making 226.7kw (304hp), a gain of 15ish hp, not quite what I was expecting.

 

CIMG67332.jpg

 

Any other ideas guys? Should I go back to a standard head and cam?

 

I don't remember if you said where the cam timing was for these runs. I'd also be interested in the ignition timing map, if its changed since it was last posted.

 

As others have mentioned, the timing seems a bit low, and usually it helps to ramp a bit of ignition advance back in after the torque peak - maybe ramp in 2 or 3 degrees from torque peak to redline. (i.e., if your torque peak is at 4000rpm and redline is 7000rpm, add 1 degree at 5000, 2 degrees at 6000 and 3 degrees at 7000).

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Cam timing is back to position 1 on the stock cam pulley, it's where it was for the last dyno tune. I tried position 3 before getting it tuned again and it seemed to loose a lot of power and was pinging slightly at high revs.

 

Timing.jpg

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