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My 91 n/a coupe and its nearly 200whp

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Old 08-11-09, 04:47 PM
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Working on my car.

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My 91 n/a coupe and its nearly 200whp

So its been a really really long time since I posted anything about my car because it's been in the works for a quite a while.

Anyway its still getting a couple tweaks here an there even now as I type this. So here is a list of mods and some other stuff.

13b street port
t2 rotor housings
side clearanced high compression rotors
6 ports (are working with vdi also)
t2 oil pump
Port match and polished intake manifolds
Haltech E8 (tuned by Nelson through Mazdatrix)
Racing beat true dual full system (headers, presilencer, y pipe and mufflers)
Spectre performance stainless steel intake cone
Racing beat springs over tokico blues
Mazdatrix 4 point strut bar with torque brace
Mazdatrix short shifter
Mazdatrix cross drilled rotors and Hawk Hp pads
Stainless steel oil cooler lines
Took out all my speakers and spare tire and a couple other things
for weight reduction. (Hoping to get down to at least 2400 pounds if i can)
No name wheels that are really heavy and Falken tires (wheels are 16's dont
know any other measurements cuz car was bought with them that way)

Thats all the mods I can think of at the moment. This car is my daily driver but I am also thinking of doing a little auto cross and stuff. Last time it was on the dyno, it was making 160 something hp at the wheels without 6 ports on 87 octane pump gas. I'm also thinking about getting a lightened flywheel, aluminum drive shaft and I might get bigger injectors and a fuel pump depending on if i'm going to need the extra fuel, and some gram lights (because i've always wanted them).

Thats about all i can think of, questions and comments as well as critisizm is welcome and if anyone cares to compare mods and horsepower/torque numbers, you are more than welcome.
Old 08-11-09, 04:52 PM
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Working on my car.

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some pics if you want to see what you're reading about.


Intake manifold


Another pic
Old 08-12-09, 10:38 PM
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Working on my car.

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Went to dyno my car today, got my results. Very good results for this car, i think.
Old 08-12-09, 11:00 PM
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very nice im doing the same kind of build
Old 08-13-09, 01:04 AM
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since you're doing something similar, i'm interested in seeing your 7 and some pics and numbers and stuff so lemme know...
Old 08-13-09, 05:20 AM
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makes me wonder how much i am putting out
Old 08-13-09, 11:35 AM
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have any pics of the street port irons?
Old 08-13-09, 12:12 PM
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So it hasn't actually made 200whp yet?

That's what I thought... it will be very difficult to break that with a streetable exhaust system and working aux ports, since the aux port shafts take up a lot of room in the intake ports.

Now go ahead and prove me wrong
Old 08-13-09, 07:52 PM
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Ok peejay, i'll prove you wrong. Add an 8 pound aluminum flywheel, an aluminum drive shaft, lighter wheels, make the intake manifold ports bigger and make a box for the intake so it gets better air, 200 is easily within reach. On top of that this is only on 87 octane pump gas and i've still got all my air conditioning stuff to take out. And what do you mean by streetable exhaust? Its 2 straight pipes all the way back with no obstructions.

And sry Rx2, i dont have pictures of the street port, i lost everything when i reformatted my hard drive and i forgot to take my pics off before wiped everything.
Old 08-14-09, 02:51 AM
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Thats a pretty harsh power band looks like it could use a better tune

Aluminum drive shaft and lighter wheels wont make a drastic enough diff to hit 200 whp

he means streetable exhaust as in quiet if you ran no mufflers you would make more power
Old 08-14-09, 07:54 PM
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FYI A lighter flywheel will NOT improve whp. I dynoed at 189.65 with a 17lb light weight steel flywheel, and 190.5 with an 8 lb flywheel. The 1 added hp most likely came from the underdrive pulley I added at the same time.
Old 08-15-09, 04:31 AM
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@hyperformance: underdrive pulley is based on the same physics as the lightweight flywheel...

@karl: 2400lbs is quite the goal. I removed everything I could including the dash and with a full tank of gas hit just barely under 2400 (I have a sunroof too). "True" dual exhaust never hits a collector and therefore doesn't need a y-pipe.

You can always switch to premix to remove the oil pump chain for less rotating mass too. I believe that while you are n/a running higher octane just caused the fuel to burn slower leaving more in the exhaust and not causing a performance gain which is why these cars were recommended 83 octane (premix brings the octane down a bit too)
Old 08-15-09, 09:17 AM
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Originally Posted by Eva001Ikari
Ok peejay, i'll prove you wrong. Add an 8 pound aluminum flywheel, an aluminum drive shaft, lighter wheels,
Doesn't add power.

If you're talking about cheating the Dynojet, it wouldn't make a significant difference at the acceleration rates involved. If you were doing 1st-gear pulls, then sure. Even a 3rd gear pull is pretty close to steady state as far as the impact of reduced rotating mass is concerned.

make the intake manifold ports bigger and make a box for the intake so it gets better air, 200 is easily within reach. On top of that this is only on 87 octane pump gas
Porting MAY help, maybe. The problem being that the restriction is in a curve so it's easy to screw it up.

I'm still not convinced that higher octane is a benefit at these torque levels. That's what testing is for though.

and i've still got all my air conditioning stuff to take out. And what do you mean by streetable exhaust? Its 2 straight pipes all the way back with no obstructions.
A/C removal doesn't add power either, it just makes it lighter, and more taxing to drive. (Being strapped in to a black car with poor airflow makes me really, really wish for A/C! If I could find all the bits I will undo what the PO did to my car and have A/C again)

I consider my exhaust to be borderline streetable. A lot of people say it's quiet, though. They don't have to live with it
Old 08-15-09, 09:24 AM
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Originally Posted by Jakor
@hyperformance: underdrive pulley is based on the same physics as the lightweight flywheel...
Underdrive pullies are so you don't overspin the water pump. Water pumps don't flow very well at high RPM, they start cavitating and this leads to overheating. What needs to be done when the useful RPM range is changed is to change the pullies so that the water pump's efficiency range is shifted back to where the engine's useful RPM range.

The Racing Beat catalog (circa mid-late 90's) had a chart showing when the stock water pump/pulley combinations would cavitate, along with stock pulley ratios. Some of the stock engines were shocking. A stock 12A setup would cavitate over 6000rpm. A proper street port on a road course might see under 6000rpm for only a handful of seconds at a time per lap...
Old 08-17-09, 09:53 AM
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It looks like VDI isn't opening until 7K. Open it at 4800-5000 or so and you'll have a much smoother average powerband.
Old 08-17-09, 01:03 PM
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Originally Posted by Jakor
@hyperformance: underdrive pulley is based on the same physics as the lightweight flywheel...

@karl: 2400lbs is quite the goal. I removed everything I could including the dash and with a full tank of gas hit just barely under 2400 (I have a sunroof too). "True" dual exhaust never hits a collector and therefore doesn't need a y-pipe.

You can always switch to premix to remove the oil pump chain for less rotating mass too. I believe that while you are n/a running higher octane just caused the fuel to burn slower leaving more in the exhaust and not causing a performance gain which is why these cars were recommended 83 octane (premix brings the octane down a bit too)
underdive pulley spins the accessory slower, which is different from it being lighter.

the oil pump chain drives the oil pump, taking it off will significantly lower the hp. premixing is a different pump.

they were NOT recommended 83 octane, every owners manual says 87 (comp book says 89). premix in the 100:1 ratio, does not impact the octane number enough to matter either.
Old 08-17-09, 01:44 PM
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Remove the oil pump chain? Holy crap don't do that! That's what sends oil to the bearings, rotors, etc. It does more than just send oil to the metering pump. You need it.
Old 08-17-09, 01:57 PM
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that dyno graph it looks really bad if you get better tuning you mite do better are you using the stock timing setup?
Old 08-17-09, 04:15 PM
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You can switch to an E-fan and change the trans and diff fluid to redline or royal purple. That should net a few ponies.

If you plan on keeping it as a daily driver think long and hard about what peejay said. If you manage to get the car down around 2400lb, you might not like it as a DD any more. It'll be hot during the day and noisy all the time.
Old 08-17-09, 08:15 PM
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FYI. i have twice now dyno'd back to back on different cars before and after underdrive pulleys, and saw an increase in power of 3whp across the top end. i don't know why, but i assume a cativating water pump is causing some significant drag for the engine to overcome.
Old 08-17-09, 09:18 PM
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Could be from increased drag, or could be because the engine was staying cooler? Although, a dyno run is probably too short to develop enough localized overheating to hurt power.

One of the Saturn racers was trying to see the power benefits of an underdrive pulley. This is a 150hp or so Improved Touring 1.9l four. The underdrive pulley made an insignificant change, less than the repeatability of the dyno. So, they did a run with the belt completely off - same effect, negligible change in power. Mind you he was turning a P/S pump too in addition to water pump and alternator. I think the total difference in power was less than 1hp.
Old 08-18-09, 11:43 PM
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In high rpm's the water pump can use upwards of 10-15hp. That's why all or most of the serious drag racers use electric water pumps that they turn off while they are racing. Think about it- you basically have a small fan in a tub of water. The higher you spin it the more drag will be made.

Ps. Don't take your oil pump chain off! Who's the moron that is saying this ****?
Old 08-28-09, 02:49 PM
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Originally Posted by rotarygod
Remove the oil pump chain? Holy crap don't do that! That's what sends oil to the bearings, rotors, etc. It does more than just send oil to the metering pump. You need it.
You can pre-mix
Old 08-29-09, 11:20 AM
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Originally Posted by Jimmy2222
You can pre-mix
if you take out the oil pump chain you won't need to.
Old 08-29-09, 12:34 PM
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Originally Posted by j9fd3s
if you take out the oil pump chain you won't need to.
umm i would like to see your car running without the oil pump chain
haha


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