93RX7_LS1

I am looking for input/suggestions/information for the vehicle and desired targets shown below.

Vehicle Details
-1993 Mazda RX-7
-2002 LS1 engine and T56 (both bone stock except for intake/exhaust)
-Curb weight – 2810bs.
-Rear end – 4.10
-Tire height – 25.3”

Vehicle use:
Daily driver (75%)
Open track (25%)

Desired Targets:
I would like to add “about” 100hp (no dyno results on current setup yet, but a trap speed of 114mph at 2,985 lbs.). Really the target is increased torque from about 2k on up with a focus in the 3500-6500rpm range.

I want a reliable valvetrain that can handle sustained high-rpm operation (peak 6600rpm), run on 93 octane, and be able to drive in stop and go traffic with the A/C on in 105°F temps w/o major surging.

Of course cost is a factor, so I am looking at what would be the most cost effective way of meeting the above goals. I know I could spend lots of money on a variety of parts that would get me to the goal, but it would not be the best way of going about it.

Current mods
-CAI (5” open element air filter to 3.5” pipe to 3.5” for Granatelli MAF inlet, stock, unported TB)
-1.75” primary long-tube, unequal length headers
-Single 3” exhaust with only a few bends, none more than 45°, no cats. (or one cat. when running at tracks with noise restriction), straight-thru muffler

Future mods (parts in hand)
-25% underdrive pulley (puking PS fluid now when hot at the track w/Turn One pump)
-Oil cooler, Accusump, remote mount oil filter (sustained running results in >265°F oil temps currently, water temp below 220°F)
-Ported oil pump
-ARP rod bolts

The first question is what heads do I “need” as a starting point for meeting the above goals? Cam lift needs to be kept reasonable (the question is what is “reasonable” for sustained high-rpm operation and minimal valvetrain maintenance?) as well as duration (what is “reasonable” for acceptable street manners given the short gearing?). My hp goal is not that lofty, can stock LS1/2/6 heads meet this goal with the cam limitations implied? It would be nice to use some stock LS6 heads with the lightweight valves if that could get me where I want to be.

Next question (coupled with head choice) is cam selection and all the things that come with it (higher lift = higher forces = higher wear = higher cost to deal with). Stock LS6 springs are good to .57", can the cam lift be kept below this so I can run these springs, make the power goal and still be street friendly?

Any input/direction is welcome. Thanks.

Bob H

iTrader: (6)

I have nearly identical goals. I'm still revising some of my mod list for the engine itself.
Which ones? I don't know exactly - I can put together the list of high $$ solutions such as the TFS or AFR heads, etc.. - but that brings the investment well out of line with my goals,(and it seems, yours).
That's why I'm subscribed to this thread as well. I have been intrigued by the heads offered here:
http://www.advancedinduction.com/AiProductsGMLS.html
Specifically, the LS2/6 heads - i.e. the 243's.
I'm interested to see the ideas.
-Bob

Old SStroker

He's info I posted on another thread:

Here are some results from a recent head/cam/intake install on an LS1 Camaro.

The stock engine with bolt-ons including 1-3/4 long tubes, SLP cat'ed Y pipe, stock 4L60E automatic with Yank 3600 TC, center mount exhaust and stock 32.3 gears made 345 lb-ft and 330 hp on a fairly stingy Dynojet.

The same bolt-ons were used for the H/C/I package. The heads were very high-end CNC ported 243's (with stock diameter valves), the intake was a FAST 92/92 and the HR cam was done to compliment the entire package.

This H/C/I package, on the same dyno, raised max torque to 405 lb-ft (up 60) and max hp to 448 (up 118). The H/C/I had 375 lb-ft or more from 3500 to 6500. That's about 92% of max torque from stall rpm to shift rpm. It was at least 40 lb-ft better from 3000 up and it was up 122 lb-ft @ 6300. That's up 146 hp (@6300) if you do the math.

The 3600 stall might now be a little much. That 92% of max torque available from 3500-6300 should make it fun on the street.

Now this is probably the very high end of what you can expect from an H/C/I package, and is is not cheap. Hell, it's quite expensive in $, but somewhat reasonable in $/hp or $/average torque and hp throughout the driving range. The heads are most definitely not a DIY project and they were not from a sponsor, so names and charts are also not included here.

This shows you what can be done with 243 heads. If you don't use the same sources and parts, your results may vary.

As far as the roller rockers, I had my say on another thread:

Roller rockers or no?

That's probably more power than you want (or need unless you are a very good track driver), but it's a high-end head/cam/intake package. It was through an automatic, so with an M6 the numbers would be higher. With less extensive head work the cost can come down and you will still have substantial power/torque increases.

The 243 (LS6) heads are the place to start. The complete valvetrain must work together. LS6 springs aren't going to hack it! Neither are very aggressive cam lobes, heavy valves, heavy springs and heavy rockers. The good news is that you don't need them if the correct parts are chosen.

This isn't a DIY project by any means. Neither is it a project for the builders/suppliers who concentrate on high peak dyno numbers.

Think "flat torque curve" like the 92% of max torque from 3500-6500 mentioned above.

Choose your engine guy carefully. I'd pick on one who has already done what you want.

This car should be either a blast to drive on track...or a real handful.

Good luck.


Jon