Single Turbo RX-7's Questions about all aspects of single turbo setups.

Suggestions For MORE POWER

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Old 03-31-09, 12:39 AM
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Suggestions For MORE POWER

I have to turn to everyone for help. I have slowly built up my FD to where I'm happy with the tune and everyday running. However, I think the car has even more and I don't know where to start to unleash it. I have run the car on C16 up to 24psi and it runs strong., I would guess over 400hp...but I want more. Here are the places I think are holding power back and I want your suggestions on what to change first:

1. Ignition: I have had in the car for years a Jacobs Rotary Master, NGK 10's, Taylor Wires and Stock coils. I hear all the stories about Jacobs but never once has it missed at high boost. Is this too old and should I change to HKS or MSD, and how much difference will the 2gen coils make.

2. Exhaust: 3-inch straight pipe all the way, no cat. I think I need 4-inch because the exhaust would keep a cheap ebay wastegate open at idle. I had to switch to a Tial 46mmm with a heavy spring to keep in closed.

3. Exhaust Manifold: HKS cast iron log style...I want reliability, but at what price did I pay in power.

4. Motor..thinking of pulling it and porting and refreshing. Compression in the 90's in both, so not dead but not fresh.

My tune is good, AFR's good, EGT's good, single T66, PFC, 880/1600, dual walpro, etc...

Your suggestion welcomed..
Old 03-31-09, 12:44 AM
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Suggestions for MORE POWER

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I have to turn to everyone for help. I have slowly built up my FD to where I'm happy with the tune and everyday running. However, I think the car has even more and I don't know where to start to unleash it. I have run the car on C16 up to 24psi and it runs strong., I would guess over 400hp...but I want more. Here are the places I think are holding power back and I want your suggestions on what to change first:

1. Ignition: I have had in the car for years a Jacobs Rotary Master, NGK 10's, Taylor Wires and Stock coils. I hear all the stories about Jacobs but never once has it missed at high boost. Is this too old and should I change to HKS or MSD, and how much difference will the 2gen coils make.

2. Exhaust: 3-inch straight pipe all the way, no cat. I think I need 4-inch because the exhaust would keep a cheap ebay wastegate open at idle. I had to switch to a Tial 46mmm with a heavy spring to keep in closed.

3. Exhaust Manifold: HKS cast iron log style...I want reliability, but at what price did I pay in power.

4. Motor..thinking of pulling it and porting and refreshing. Compression in the 90's in both, so not dead but not fresh.

My tune is good, AFR's good, EGT's good, single T66, PFC, 880/1600, dual walpro, etc...

Your suggestion welcomed..
Old 03-31-09, 02:05 AM
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That is borderline low compression. You could rebuild and port out your motor or go with a bigger turbo and A/I.
Old 03-31-09, 02:13 AM
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You should do a retune from a reputable and competent rotary tuner.

Its always best to do a tune up and re-dyno the car on your street tune and see what your numbers are....


Im not familiar with a T66 but if you are guessing in the 400's with C16 and 24psi... it seems a bit low as even a small GT35R can get over 450, and most who run aggressive tunes on stock twins are making clost to 380-400 on non-sequential
Old 03-31-09, 06:50 AM
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Originally Posted by cptpain
You should do a retune from a reputable and competent rotary tuner.

Its always best to do a tune up and re-dyno the car on your street tune and see what your numbers are....


Im not familiar with a T66 but if you are guessing in the 400's with C16 and 24psi... it seems a bit low as even a small GT35R can get over 450, and most who run aggressive tunes on stock twins are making clost to 380-400 on non-sequential
I agree its low, but we have tuned the best we can on the drag strip. The car is in the islands and no dyno on the island. Do you have an experience with any of my mods not performing?
Old 03-31-09, 06:53 AM
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Originally Posted by WaachBack
That is borderline low compression. You could rebuild and port out your motor or go with a bigger turbo and A/I.
Thanks..I already have new Precision T88 and a new CooolingMist kit on the way.

So thats one vote for rebuild and porting..anyone else..
Old 03-31-09, 07:29 AM
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different turbo and manifold. leave the exhaust as is.
Old 03-31-09, 08:54 AM
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1+ on a port.. Depending on what you want your car for street or track. I think if you going to use it for street a good full street port would be best with the T88 and cooling mist. You should see 450+ HP. I might be wrong
Old 03-31-09, 08:59 AM
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You said on the strip. What are your ET's? Trap speed? Depending on these, someone can give you a rough estimate of what whp you're making. Also, can we have exact (as close as possible) compression numbers? "in the 90's" is very arbitrary. It could be 98/99 on both rotors, or 90/91 on both rotors. Either way, we need more accurate information.

My suggestion: Get a competent rotary tuner to come to whatever island you're on and get a good street tune. You won't have an exact hp number, but you'll know that you have a solid tune.
Old 03-31-09, 10:41 AM
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Buy a different turbo. Precision 6765!



Just for you, Sean
Old 03-31-09, 12:33 PM
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at 24psi with a good tune you should be over 500hp..maybe closer to 600...and you want more power? Have you dyno'd on the 24 psi and that tune? I dont know but i get the feeling your tune isnt spot on you hence you are not getting the maximum use of your 24psi and c16
Old 03-31-09, 12:48 PM
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If you are going T88, a large port or half-bridge will really help spool your turbo.



Originally Posted by 207
Thanks..I already have new Precision T88 and a new CooolingMist kit on the way.

So thats one vote for rebuild and porting..anyone else..
Old 03-31-09, 01:55 PM
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are you in Miami? what 'island' are you talking about?
Old 03-31-09, 11:02 PM
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Originally Posted by whitey85mtu
You said on the strip. What are your ET's? Trap speed? Depending on these, someone can give you a rough estimate of what whp you're making. Also, can we have exact (as close as possible) compression numbers? "in the 90's" is very arbitrary. It could be 98/99 on both rotors, or 90/91 on both rotors. Either way, we need more accurate information.

My suggestion: Get a competent rotary tuner to come to whatever island you're on and get a good street tune. You won't have an exact hp number, but you'll know that you have a solid tune.
The best time on the 1/8 track is 7.72 with a 2.00 60ft....
Old 03-31-09, 11:03 PM
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Originally Posted by cptpain
are you in Miami? what 'island' are you talking about?
Nassau, Bahamas...your welcome to come down. Cameron has been down already and worked on the car for a day and said it was "solid"
Old 03-31-09, 11:08 PM
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Originally Posted by BluRR
at 24psi with a good tune you should be over 500hp..maybe closer to 600...and you want more power? Have you dyno'd on the 24 psi and that tune? I dont know but i get the feeling your tune isnt spot on you hence you are not getting the maximum use of your 24psi and c16
I can upload my IGL and AFR map from a run at the track ...no dyno to work with at this time.
Old 03-31-09, 11:15 PM
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Unhappy

Moderator...Please delete this post..it is duplicate..I must have posted twiced. Sorry...
Old 03-31-09, 11:34 PM
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Originally Posted by killahrx7
different turbo and manifold. leave the exhaust as is.
THanks..thats one vote for turbo/manifold and one for ported engine
Old 03-31-09, 11:35 PM
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Originally Posted by ScorpionT
Buy a different turbo. Precision 6765!



Just for you, Sean
THanks .... 2 votes for turbo, 1 for proted engine
Old 04-01-09, 03:50 PM
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Probably in the engine tune and engine condition.

What turbine a/r are you running on the T66?

If you are running 24psi a 4" exhaust would help a lot, especially if you are using a P trim turbine wheel.
Old 04-01-09, 05:09 PM
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Originally Posted by 1Revvin7
Probably in the engine tune and engine condition.

What turbine a/r are you running on the T66?

If you are running 24psi a 4" exhaust would help a lot, especially if you are using a P trim turbine wheel.
I just realized today that I forgot we upgraded to a P-Trim T76 during christmas...it does have a 3" v-band outlet. Do you think the 4" will make a difference?
Old 04-01-09, 06:00 PM
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Originally Posted by 207
I just realized today that I forgot we upgraded to a P-Trim T76 during christmas...it does have a 3" v-band outlet. Do you think the 4" will make a difference?
A T76 @ 24psi should smoke the street tires all the way too 100+mph. Yes a 4" exhaust will do wonders for that large of a turbo. So what turbine a/r are you running?
Old 04-01-09, 07:31 PM
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Originally Posted by 1Revvin7
A T76 @ 24psi should smoke the street tires all the way too 100+mph. Yes a 4" exhaust will do wonders for that large of a turbo. So what turbine a/r are you running?
It is a 0.96..its hard to drive on drag radials, but I have in worst RX7 puttin out 500hp on the dyno..
Old 05-19-09, 07:47 AM
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Okay..it has been a few weeks and I upgraded the following:

1. 4 inch exhaust with Borla muffler, no cat...really nice work, will post pics later
2. Upgrade turbo to PT-76 a/r 0.96 from Turbonetics T72, a/r 0.96
3. NGK R6725-115 spark plugs all around--(damn thats expensive)

The car needed retuning in the boost over 8psi as it was running lean. I was surprised how much more fuel was needed to get the AFR to 11.5 at 18psi.

Anyway went to the track and after 4 hard attempts the car runs a full second slower in the 1/8th and feels really sluggish....

Time for the flamethrower.....

I was wondering if the ignition or wires are going. The car had minor breakup at the launch but ran clean the rest of the way. I would think if the ignition or wires were bad the car would breakup going down the track...

The only real difference in the car running was it idles about 200rpm's higher than before. It idles at 1000rpm, I thought there might be a leak but could not find one.

Any suggestions on why the car would have less horsepower with a big exhaust and turbo..
Old 05-19-09, 09:21 AM
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What was the MPH difference before and after the changes? Forget the time.


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