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Index > Engine/Drivetrain > Thread: Just got a repu and i now have some goals
Thread: Just got a repu and i now have some goals
Mike_Rudy


1st Gear
Posts: 22
posted October 11, 2005 11:41 AM

Just got a repu and i now have some goals

Well i just bought my repu and what is the first thing most people do when they get a new vehical? Take it apart of course lol. What i am wondering is can i get my 1974 repu into the low 15's in the 1/4 mile without opening up the engine.

I was thinking complete exhuast with header, open up the intake a little bit, mechanical secondarys, possibly open up the venturies a little bit also. Then converting to the electronic distributer and running the msd system on the leading plugs.

Have any of you taken your repu's to the strip? I don't want mine to be extremely fast or anything i just thought low 15's would be nice

       
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klaus42


Rotorhead
Posts: 1877
posted October 11, 2005 01:51 PM

You'll want to read some other threads here...

...both older, and more recent, in the engine as well as chassis/suspension sections.

You'll need: That E-ignition dizzy, but not that MSD box; LSD in the rearend, most definitely; the RB header, and as straight a shot possible back of it; a different (larger)carb/intake altogether...

Then, you'll be wanting to get into your engine to get her ported!

       
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Mike_Rudy


1st Gear
Posts: 22
posted October 11, 2005 02:14 PM

Well i keep seeing the streetported 12a in my rx7 and wanting to stick it in there lol. But i think before i port i will run 7 or 8 psi either supercharged or turbocharged. So you dont think a ported intake, and a ported nikki or stock carb would work? The nikki i have on my rx7 flows 430 cfm. It ran a 14.71 with an open rear end, but when we put in the lsd it ran a 14.47. The car is also very heavy for a first gen at 2609(has a big sterio system in it)Thats why i was thinking i should be able to get lower 15's withour porting. The repu is a bit heavier but having 4.625's will help.

Mike

       
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klaus42


Rotorhead
Posts: 1877
posted October 12, 2005 11:41 AM

'Anything' can be made to 'work', *but*...

...I have no idea of precisely what combo of mods will result in your desired strip time, and can only comment as to what I consider to be biggest bang-for-buck, common-sense improvements. Sometimes it makes sense to try to retrace the footsteps of rotary racing predecessors, modding 30 year old carbs... sometimes, one's time and energy is better spent going with 20 year old technology... IMHO.
That said, first things first for a stock-ported 13B REPU: Sticky rubber, the RB header, and electronic ignition... plus careful tuning!
RE: 12A : Don't do it! It's a small step backward...

       
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Brad


Rotorhead
Posts: 1672
posted October 12, 2005 04:51 PM

quote:
Well i keep seeing the streetported 12a in my rx7 and wanting to stick it in there lol. But i think before i port i will run 7 or 8 psi either supercharged or turbocharged. So you dont think a ported intake, and a ported nikki or stock carb would work? The nikki i have on my rx7 flows 430 cfm. It ran a 14.71 with an open rear end, but when we put in the lsd it ran a 14.47. The car is also very heavy for a first gen at 2609(has a big sterio system in it)Thats why i was thinking i should be able to get lower 15's withour porting. The repu is a bit heavier but having 4.625's will help.

Mike


I agree with Klaus. THe truck weighs 2850lbs so it needs the torque and hp of the 13b. I'd only put a 12a in there if it had a third rotor ;). U can use your ported plates and pre-86 rotorhousings and any pre93 rotating assembly or look around for a good B motor.

The Nikki is okay on a B motor and will work but is smaller than the rx4/repu carb.

Electronic distributor, MSD, and good fuel filters is a start. We're working on a TORSEN LSD upgrade for REPU and hope to have some news soon.


____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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SkinnyLou


Newbie
Posts: 10
posted October 12, 2005 05:22 PM

Have to agree....

on the RB header being one of the first essentials. Just replaced the header with exhaust and feel plenty more power. Should have done it much sooner!
____________
SL

       
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Mike_Rudy


1st Gear
Posts: 22
posted October 12, 2005 06:31 PM

What do you guys thing about traction bars? I wouldn't put them on if i didn't already have em, but i am tepted too, they are thoughs 30$ summit ones, they were on my rx3 when i bought it. If i stick with a ported nikki or stocker, should i port out the stock intake, i have heard that matching it to the gasket will give a bit better top end but you will lose almost all your bottem end power. As for tires, i got a set of sticky kumho tires that i think i will stick on. Id love to pull then engine apart and do some porting but whenever i do that i cant stop myself from massively porting it. On my last Rx7 i sold, i took it apart with the intension of just cleaning up the ports and ended up with a half bridge port lol

       
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Brad


Rotorhead
Posts: 1672
posted October 12, 2005 11:06 PM
Edited By: Brad on 12 Oct 2005 23:11

traction bars....

They serve their purpose in a straght line but don't work well when cornering. They'll mess with the spring rates when they hit. Much better way to go is composite monoleaf rear leaf springs. People who put them on their cars say they don't need traction bars, no spring wind up with composite. And they control lateral axel movement much better. Plus lighter, more responsive, do better under braking too.

http://flex-a-form.com/ can make u a custom set.

I ported a 12a Rx3 manifold for my 81 rx7 streetport. DID make a difference, more HP especially at top end. To make up for the larger passages reducing torque somewhat, I had a 1" thick plastic spacer made. Bought the material at a plastic shop and took it and new gasket to a machine shop and said "cut this out". It also isolated heat, carb didn't get as hot with the plastic spacer. I think I used Delrin.
____________
-brad-
74 REPU Lawn Green
81 Rx-7 racecar. 12a J-
Bridge

       
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Mike_Rudy


1st Gear
Posts: 22
posted November 18, 2005 07:09 PM

well the 13b that was in it has 0 compression in the front and 50 in the back,so we desided to put my mild/wild 12a streetport engine in it since it has no miles on it. We are also going to put in the 5 speed with it. I know a 12a is a step back from the 13b, but the 12a has a pretty wicked streetport and also has carbon apex seals so i will be able to rev the hell outta it.

       
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