Rxmfn7

Hello all. For a little background info on myself, I have been building turbo rotaries for the past ~6-7 years or so, and am now looking to do a LS1 swap into my '94 Rx-7. I must admit that I dont have a ton of experience with these engines, which is why I am here for advice. I would like to raise the power curve of the LS1 up to be safely making power at ~7k rpm. With the 4.10 rear end in the Rx-7 ( that I would like to keep), it winds the LS1 out fairly quickly. I dont mind spending the money on a good head and cam setup that will do what I want, but I just would like to be pointed in the direction of what to look for. I dont want to be worried about bending pushrods or valve float pushing higher RPM. Also I would like a setup that will still pass emissions. Thanks for any advice. I have also attached a picture of my FD that this will all be going into.

HeapaShifter

iTrader: (2)

To run 7k you'll need upgraded pushrods, valve springs, and rod bolts. Valves and connecting rods should hold up fine.

You'll also want to make sure you get a cam that makes power up there.

Rxmfn7

Thank you, any advice as to what brands would be the best to buy? Im still looking into a head/cam setup that will pull that high, while still being drivable and putting down the power I want (450-500rwhp).

LS1-450

iTrader: (33)

Are you going w/ a manual 6 speed transmission? Even w/ a 6 speed, you may find 4.10's a bit unruly in an LS1 powered RX-7. Maybe not, but, it's something to think about. Can also say that you may find the power you want @ 6,500 RPM & fuel shut off @ 6800 on a mild cam/good head without any other internal mod's. As you can see, my Miata is an A4 w/ a 3.55 rear end. Even w/ the automatic, my car makes 390 RWHP & 400 #-ft tq & I really don't know what I could do with more power. That's about its' usable limit. The car weighs 2,750# & has a subframe & built suspension. Your Rx-7 could probably handle a bit more w/ the proper suspension & sub-frame bracing, which of course are a must for little cars making loads of torque. A more agressive cam than I have would get you there. Although, the emissions gets a bit more tricky if you get too wild w/ the cam. My car is emission legal to Ca spec's. I don't mean tricking the rear O2's 'cuz the cats are gutted. I mean all emissions equipment works properly. Hope this is helpful & good luck w/ the build.

edit: I wrote this @ the same time you were posting the 450-500 RWHP. I could see 430-450 w/ an agressive cam & no cats running up to 6,500 RPM, but, you'll need the 7K if 500 RWHP is a must.

hotrodrx7

iTrader: (13)

I think your biggest problem in making that kind of power will be passing emissions. I am making 406 HP in my RX7 with a 4.10 and it's perfectly streetable. There is a lot of throttle between idle and WOT.

Rxmfn7

Thanks for the response. Yes I am going with the T56 Trans. I can always tone it down a bit and go with 3.90s from an auto car, but thats not a huge gearing change. As I said I am still looking into what setup exactly I am going to run with. My car is currently making a bit over 300RWHP on just a few mods to the stock 13B-REW, and ~400RWHP is fairly easily attainable with a turbo swap, although much more after that is where rotaries dont like to last too long Im just looking for a nice reliable setup that I can drive but still make gobs of power. 450RWHP is my goal, anything more would just be icing on the cake. That much power/torque in a ~2700lb car with 4:10s will still be stupid fast.

LS1-450

iTrader: (33)

One thing to keep in mind & I'm sure that you are aware of, making 400 RWHP & 200/250 #-ft. (estimate) of torque is a much different car than one capable of 400 RWHP & 400 #-ft of torque. If 450 HP is the number & you want to save some $ then, a head/agressive cam on otherwise stock internals @ 6,500 RPM will be close. Rear wheel tire size will then be the limiting factor to traction on a stout frame/suspension. Agreed, it will be stupid fast & a hell of a lot of fun. Please keep us posted on your progress.

300bhp/ton

I can't see you making near 500rwhp and still full emissions legal on a n/a 346ci, larger displacement or with the addition of FI, yes.

And as noted, 400rwhp rotary power is not the same as 400rwhp from a large displacement OHV V8. Not too mention the durability side of things, even Evo's and STi's need a lot of regular maintance at the level of performance.

If you're really after that kind of power, you'll want good bolt on's such as LT's, exhaust, high flow metal matrix cats (Random Technology or Maganflow), 90mm intake and TB (FAST/Nick Williams), good heads like AFR or ET, a pretty wild cam (will lack low end torque - TSP MS3, Thunder Racing Trak/T-Rex, LG cams, F14 or a custom grind) plus all supporting mods such as fuel, tune and valve train requirements. Also at this level of HP forged internals may be well worth their money.

Do you already have a LS1? If not it might be worth just looking at buying a stroker engine such as a 402ci, TSP sell them with the aluminium block, all you'd need is some half decent heads and a sensible sized cam and you'd easily meet your HP goals and still retain good driveability.

Mike00FRC

iTrader: (1)

Just as an FYI, if your concerned about emissions. When I had my 98 WS6 I was at the limit for emissions with the following cam and supporting mods. Granted, with a perfect tune, you might be able to go a little bigger, but probably not very much so. This was on the PA roller emissions (IM240?).

98 WS6 M6
ThunderRacing TR224 (224/224/.563/.563/112)
CompCams 918 springs/Ti Retainers/7.40 pushrods ~ 6600 rev limiter
Longtubes with RT cats, LS6 Intake, ARE Stage II heads (2.055/1.60),
Exhaust, lid, stock MAF/TB, ls1edit

With that setup, I put down 406/380 on a pretty conservative dyno, but that was also a while ago. With the current advancements in head porting/choices I could see around 425+ on a similar setup. Should make for a hell of a ride in an RX-7... very good powerband with that cam.