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Old 12-20-2011, 04:03 PM   #21
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A larger exhaust is not going to give you more lower end torque. There is a reason road racers use smaller exhaust systems than drag racers.

In saying that however, it is possible that the 2.5 inch exhaust is not the ideal set up with your blower. It seems to be with all out N/A applications on the road coarse. Only experimenting will know for sure.

If you have the money to do this, doing the baller mods like electric water pump, evac system, or lighten the load on your valvetrain/powertrain will give you some power and torque across the entire power band. It is not cheap, and it is not going to net you a ton of power. Typically last resort methods when all other options have been exhausted. Just throwing that out there.

Put your car on a diet. That will be like adding power and torque.
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Old 12-20-2011, 04:24 PM   #22
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Quote:
Originally Posted by Savington View Post
Probably LSA (lobe separation angle). More LSA = more overlap IIRC.
backwards. LSA is the angle distance between peak of exhaust lift and of intake. More LSA = less overlap.

It's a pretty meaningless spec by itself. Overlap, intake closing point, and exhaust opening point are more useful. You can't derive overlap from LSA without knowing the opening and closing profiles. LSA is just easy to measure when you're holding an old-school single-cam engine's cam in your hands, thus the measurement's popularity.
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Old 12-20-2011, 04:27 PM   #23
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Yeah I have all that info it's just sitting on a paper in my car folder at home. Out of reach for the time being until I get back to Canada.
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Old 12-20-2011, 04:54 PM   #24
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falcon, did the new cams increase or decrease your torque at 4000 RPM?
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Old 12-20-2011, 05:53 PM   #25
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Don't know.. the motor was built and installed with the cams from the get go.
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Old 12-20-2011, 07:57 PM   #26
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I'll guess they decreased torque at 4000. You may be better off with stock cams.
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Old 12-20-2011, 08:29 PM   #27
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Perhaps... I still have stock cams however it took a lot of work to find and modify all the shims for the lifters. I don't know if I want to go through that again.

Sav's right... I think I'll just do a few easy things and the car needs a re-tune anyways and leave it be until I build myself a stroked out VVT motor :P..
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Old 12-20-2011, 08:40 PM   #28
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Quote:
Originally Posted by miata2fast View Post
A larger exhaust is not going to give you more lower end torque. There is a reason road racers use smaller exhaust systems than drag racers.
I thought that was mainly because road courses often have sound limits and drag strips usually don't?

--Ian
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Old 12-20-2011, 08:44 PM   #29
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Mill the head?
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Old 12-20-2011, 08:45 PM   #30
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Weld washers to the pistons?
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Old 12-20-2011, 08:47 PM   #31
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Who are you and why are you posting here?
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Old 12-20-2011, 10:22 PM   #32
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Who are you talking to?
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Old 12-21-2011, 07:10 AM   #33
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You.

Weld washers to the pistons? Really?
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Old 12-21-2011, 07:45 AM   #34
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Aaron, what about finding a set of HLAs and stock cams, taking out your current cams along with the lifters, substituting HLAs, and seeing what it does for low-end power? You don't need solid lifters to do a 6500rpm dyno pull for low-end torque comparisons. If it makes a big difference down low, you can spend the time setting up a solid valvetrain for stock camshafts so it will rev again. If it makes no difference, or an insufficient difference, you can just drop the Maruha cams/lifters back into place and forget about it.
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Old 12-21-2011, 07:47 AM   #35
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That's a good idea... I didn't think of that. I should still have my lifters kicking around somewhere in a bag. And I know I have the cams. BTW, not that it really makes a big difference but my cams/lifters aren't maruha :P... they were way to baller for me. I have mazspeed lifters w/ supertech shim and ground cams done locally.
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Old 12-21-2011, 07:51 AM   #36
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Falcon you missed it sorry buddy.

Dann
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Old 12-21-2011, 05:36 PM   #37
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Quote:
Originally Posted by falcon View Post
You.

Weld washers to the pistons? Really?
Milling the head will increase cylinder pressures which will increase torque.

Welding washers was a joke. Old timers used to try it when they couldn't order custom pistons.
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Old 12-21-2011, 05:46 PM   #38
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Smaller pulley on the sc, bigger one on the crank (unless you're over spinning the sc right now), a wastegate set at your correct psi level to prevent you from over boosting at high rpms...yes wastegate will be open to remove extra air at redline.
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Old 12-21-2011, 05:49 PM   #39
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Wait a minute here. Are you seriously suggesting to install the stock cams in place of your hotter cams?

If you are having a problem with power delivery, it sounds to me like you need a final drive gear change. Get your rpms in the range they need to be before doing something stupid like making less power.
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Old 12-21-2011, 05:54 PM   #40
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Quote:
Originally Posted by codrus View Post
I thought that was mainly because road courses often have sound limits and drag strips usually don't?

--Ian
Drag racing is always foot to the floor. Road racing spends a lot of time at lower rpms and part throttle.

Squeezing the exhaust down gives you more torque at the lower rpms and part throttle. Smaller exhaust is a compromise that pays off on the road coarse, but penalizes the drag racer.
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