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Discussion Starter #1 (Edited)
Whats up D family.

Im ready to enter the world of boost swith a d15 mini me build. Timing belt broke, tired of having tig weld cracks in my 700 dollar header( ykw)so ready to give it a shoot. Ran across a t28 turbo off an 88 RX7 turbo II and welded on a d series ex manifold. I have searched high and low and not run across many turbo builds with P29's. I am not looking to be a dyno king just want a car that spools up quick, is fun to drive and makxe around 160tq/ 210whp. According to my math I'm around 10.5/1 comp ratio but just wondering has any boosted a reliable setup with P29's

Thanks and appreciate feedback
 

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97 civic lx
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P29s have too high of a dome, slapping on a turbo on that shit would require the tuner of tuners and perfect timing.
Nah, just your average Joe tuner can't do it. Or won't. For his goals, he won't have To run a whole lot of boost. May even get away with just adjusting the fuel maps and slightly tweaking the ignition tables.
 

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Discussion Starter #6 (Edited)
Thanks for the feedback and I live in Suwanee,GA area and we have access to one of the best tuners in SE named ED Senf that tunes SCCA, Speed World Challege cars etc so no worries there. Just have not seen many boosted setups/results for P29's so figure i would check with dseries familia first. I feel 10.5/1 isnt too high with such a small scfm turbo.??

Keep the feedback coming and i am searching but want feedback from my main family first.
 

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don't the p29s cause really uneven combustion?
 

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You will also need to run E85 or even E98 if not C16. At minimal I would run meth injection. If you can keep the detonation away you will be fine.
 

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Just curious but was the T28 an aftermarket turbo or was it stock? I am asking because the RX-7 never came with a T28, EVER nor did they ever come with a Garrett turbo. Honestly it would be an extremely odd match for a rotary. A T28 is a small turbine size turbo and the RX7 has an excellent exhaust pulse characteristic and they can spool relatively large turbo with very lil effort. The old quick spool Hitachi HT18 S2S is basically a T3 turbo but it uses a larger stage 2 turbine design. In comparison this turbo would be responsive and have excellent torque characteristics on a rotary. On a D16 they would not spool as favorably for an OEM like setup.

Just pointing this out now before get started.
 

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2005 Legacy GT
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First question (maybe I missed it) USDM d15 or JDM d15.

If it's a USDM (short rod) d15 then the p29s are going to sit in the hole which is going to screw with your flame front and combustion chamber dynamics.

If it's JDM (uses longer d16 rods) or a d15z1 (also longer rods) that shit is going to stick out of the block and give you a stupid high compression ratio.

Second question ... which head z6 or y8. This will also change your compression ratio, the y8 will net you ~0.4 higher CR, but IIRC will give you a better quench pad and so will not be as much of a problem as you might think.

If you've done that much searching and not found any turbo builds using those pistons ... there's probably a good reason.

Are you planning on running forged internals? If not you may have to step back your power goal ever so slightly if you have the thin USDM d15 rods, I hear they like to start failing around 200 whp. I would also recommend some ARP rods bolts in that case for a little extra insurance.

Take a look at my build, it's right about where you want to be hp/tq wise on a smaller turbo. I'm running about 10.2:1 CR and it's taking it like a champ. Also take a look at 90civichillclimber's build, proof that high comp + turbo works like a charm.
 

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Brokedick Millionaire
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USDM D15 with FJT rods, short P29's, lots of tuning.

10.85:1 compression (Z6/Y7 head)

Better off to start with a D16 bottom end.
 

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1. search

2. p29's are probably to high compression for boost, most people go down not up.

high compressions build right now seem to be running between 9:1 and 10:1 what a small/medium size turbo.
explain a certain 12.5:1 boosted combo running on here, also for sale.

Yes it is built, but it is possible.
 

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Discussion Starter #15
Lots of good info in your replies and in regards to turbo it is old but from what I researched (posibbly wrong) 88 RX7 Turbo was T28 but I received this info off a RX7 forum while using Google Search "88 RX7 Turbo type Specs" . I pulled many years ago and just kept around for a time such as this but Turbo is stock. Cylinder head is a Z6 and is going to be ported by Dustin at Performance Porting . It is a USDM D15 and pistons do sit a little below block deck and am going to use ARP rod bolts and have pistons/rods Cryo treated. I will post a pick of what i have once im at home.

Really appreciate everyones insight.
 

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What P29s are they? OEM P29s will sit 1.7mm below the deck, which is horrible for a number of reasons.

Because it is in a D15 with stock rods, the piston dome is not going to have much of an effect on the combustion, since they will be sitting so low.

I wouldn't recommend this setup because of the rods, not the pistons. Tuning the timing will be critical. A bit too much and you WILL bend your rods and/or break your ring lands.
 

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Post some pictures and we can verify but I'm positive the stock turbo was a hitachi HT18. I'm pointing it out as this turbo will react considerably different then you expect.
 

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Post some pictures and we can verify but I'm positive the stock turbo was a hitachi HT18. I'm pointing it out as this turbo will react considerably different then you expect.
i was almost postive that my buddys FC 10th anniversary had a t28, and that thing ran stupid low boost pressure..
 

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i was almost postive that my buddys FC 10th anniversary had a t28, and that thing ran stupid low boost pressure..



Almost. Its a ht18. When mapping turbos for rotary motors you double the motor displacement. A 1.3 is really a 2.6. Imagine a t28 on rb26dett. Just one of them.

Here's a comparison of a t28 setup on the right compared to a ht18 in the middle with a larger t4 compressor. Also a t25 on the left.

 

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i stand corrected, thats good to know tho, i have a good feeling that would be over kill for a DD civic, but none the less
 
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