acceleration for '72 rsr tribute with a 3.6l

[tradin1]

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i am on the fence in putting a turbo motor, Vram 3.6l, or the Vram 3.6l with PMO's and RS cams.

it will be a DQ cruiser, so i want stoplight to stoplight fun. i already have a 996tt that has the UMW 3b kit on it so i already have a MONSTER for fun.

my fear is that if i do not go with the turbo, i will be severely disappointed; but i keep reading about the NA "experience"...lightweight car with awesome sound.

this draws me to the PMO's/cams more and more, as i love the sound of the NA pcars.

i have never ridden in a lightweight NA Pcar before, and do not know anyone that can take me for a ride so that i can make an educated decision. if there is anyone in dallas that can give me a ride, ill buy lunch and promise to chew your ear about pcars the whole time!

so, what kind of acceleration can i realistically expect with the above setups? the car has a 915 w/ LS and the car should weigh around 2500lbs when done. if i go with the turbo, i will use the G50.

thx.

[petevb]

Originally posted by tradin1
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i am on the fence in putting a turbo motor, Vram 3.6l, or the Vram 3.6l with PMO's and RS cams.

it will be a DQ cruiser, so i want stoplight to stoplight fun. i already have a 996tt that has the UMW 3b kit on it so i already have a MONSTER for fun.

my fear is that if i do not go with the turbo, i will be severely disappointed; but i keep reading about the NA "experience"...lightweight car with awesome sound.

this draws me to the PMO's/cams more and more, as i love the sound of the NA pcars.

i have never ridden in a lightweight NA Pcar before, and do not know anyone that can take me for a ride so that i can make an educated decision. if there is anyone in dallas that can give me a ride, ill buy lunch and promise to chew your ear about pcars the whole time!

so, what kind of acceleration can i realistically expect with the above setups? the car has a 915 w/ LS and the car should weigh around 2500lbs when done. if i go with the turbo, i will use the G50.

thx.

Not in your area, so no ride, but I'll give you a data point- my '70 with a 3.6L was good for ~3.7 to 60 and ~12.7 at 113 in the quarter. 310 hp Vram, 915, 245 rear tires, 2200 lbs plus driver or so. Concentrate on getting the weight down, not on power, as that's what makes the conversions special. Also, the 915 will break after time used for stoplight racing, so if that's really your goal consider the G50. IMHO stoplights, while fun, are not the reason to get a conversion. The real reason is that while you plant your foot and hold on in your turbo, you DRIVE a conversion. Sideways, (on an autocross course or track) if at all possible!

You'd get better response on the tech forum, btw.

-Pete

[gestalt1]

in this week's autoweek they reviewed the carrera gt3. it has 415hp and weighs 3075 lbs. the acceleration was under 4sec to 60. if you calculate the power/weight ratio it comes to 7.41lbs for each hp, with a 2200lb car you would need 297 crank hp to equal that, very doable w/ a 3.6 with good exhaust and intake systems. i'm on the side of NA, no turbo. why go with the added complexity?

[tradin1]

thx for the responses...

by stoplight to stoplight, i did not mean as in street racing. i was leaning more towards, on ramps, passing cars, and road driving in general.

the suspension will all be erp with jrz coilovers, same setup i have on the 996tt.

the tranny has been rebuilt with L/S, with WEVO upgrades.

the ITB sound great, and i hear they give incredible throttle response. this is what i would really love to have, just unsure of the performance potential.

pete, what all did you take off the car to achieve the 2200lbs? also, what intake system are you using, what suspension, and tranny? thx for the input.

can someone move this to the tech section, as i do not want to double post...

[herman maire]

I cant really help you out with your choice but, I am building up a crazy early car (RSR body) with a 98 993 VRAM motor. I am going to run this motor while I build a wild 3.6 TURBO motor based on a 993 N/A motor.

I am thinking 550hp low boost and maybe 600-650hp with the boost cranked up. This is going into a light weight early 911, but again... I will be running the 3.6NA motor for a while. Oh, and I might use a tired 964 to build this project on ( because of the g50 trans) and back date the body.

Any pics of the 996?

Good luck

[petevb]

Originally posted by tradin1
thx for the responses...

by stoplight to stoplight, i did not mean as in street racing. i was leaning more towards, on ramps, passing cars, and road driving in general.

the suspension will all be erp with jrz coilovers, same setup i have on the 996tt.

the tranny has been rebuilt with L/S, with WEVO upgrades.

the ITB sound great, and i hear they give incredible throttle response. this is what i would really love to have, just unsure of the performance potential.

pete, what all did you take off the car to achieve the 2200lbs? also, what intake system are you using, what suspension, and tranny? thx for the input.

can someone move this to the tech section, as i do not want to double post...

If it's the aluminum case 915 is should be fine, the mag case could stil be ok with lots of upgrades and good treatment. The G50 would be better.

My 2200 lb car (sold < 1 month ago) ran
Susp- JRZ 1x adjustables, hollow T bars, TRG sways, ERP bushings.
Tranny- Al case 915, re-geared w/ wevo gateshift, shifter
Engine- Vram with RS hydraulic cams, headers + exhaust
Brakes- 930
Weight- RS look body, all steel except bumpers. RS interior, light battery, light bumpers, Recaro racing buckets, no AC, no radio.

My new car (just about ready) runs
Susp- JRZ 2x ajustable (worth it over the 1x), coilovers, TRG Swaybars, 935 susp.
Tranny- G50...
Engine- Vram with solid lifter cup cam, RS valves
Brakes- ...
Weight- cage, fiberglass body, etc- ~2000 lbs

I think you're correct in leaning towards the ITBs, but I'd suggest you get different pistons and a big cam to go with them to make them worth it. The one issue with getting the car very light is that it becomes harder and harder to get the weight balance and handing correct. I believe you want to keep as much weight forwards as you can (less than ~62% on the rear), which means you'll want to be ruthless with weight behind the rear axle. Exhaust/ rear bumper/ engine stuff in particular. ITBs vs VRam, light flywheels, etc can save lots of weight there.

My car was a blast on the road, but also a real handful- I tried not to push it there too much. You need to be really on your game to use even 80% of a car like this on the road- and the vast majority of drivers have no business trying. If you do something dumb there is no safety net, and they are tin cans compared to a modern car in a crash.

[tradin1]

Can someone recommend a good set of solid lifter cams that will have a good idle for 95% street driving.

what kind of power can i expect with ITB's and said cams? 300, 320, 350???

can someone recommend a lightweight flywheel that will work in between the 915 and 993 3.6l Vram motor?

as for exhaust, i was going to put cat bypass pipes, and free flowing exhaust. i was told the exhaust manifolds are about as good as it gets for the 993 motor while still having heat...does everyone agree, and if not, what do you recommend?

are the hollow t-bars worth the extra expense? how much weight do you save?

what about going full coilovers does it ride noticeably better, or would i save any weight?

what is the benefit of the 935 suspension, and what pieces do you utilize?

thanks for the help.

[petevb]

Originally posted by tradin1
Can someone recommend a good set of solid lifter cams that will have a good idle for 95% street driving.

what kind of power can i expect with ITB's and said cams? 300, 320, 350???

Too tough to say without knowing the rest of the motor. Question 1 is how much are you willing to spend? You can build a 430+hp N/A motor if you want to...
If you keep the 993 pistons I'd suggest the 993 supercup solid lifter cam, as I have in my motor. The idle kinda sucks with the Vram, but cleans up with ITBs. If you have different pistons you could go even wilder.
In my motor (with RS valves) I make 320-330 hp with the Vram. You can make a bit more with ITBs...

can someone recommend a lightweight flywheel that will work in between the 915 and 993 3.6l Vram motor?

Instant G and Patrick Motorsports sell these. I happen to have an extra new Instant G one from when I switched from 915 to G50.

as for exhaust, i was going to put cat bypass pipes, and free flowing exhaust. i was told the exhaust manifolds are about as good as it gets for the 993 motor while still having heat...does everyone agree, and if not, what do you recommend?

I feel you can probably find 5+ hp by going to B&B headers or maybe an instant-G header system, especially on a hotter motor. Not cheap power- I may know where there is a used B&B header system for about $700.

are the hollow t-bars worth the extra expense? how much weight do you save?

Few pounds. Maybe not worth it on a street car unless you're doing everything.

what about going full coilovers does it ride noticeably better, or would i save any weight?

Small amount of weight and ride improvement, mostly good for easy spring swapping and ability to switch to 935 stuff, which does save ~10 lbs. But you need to stiffen the chassis, so probably not good for a street car.

[tradin1]

what pistons do you recommend? i assume they would raise the compression, what is stock, and what would these take me too?

will the ITB's be hard to keep running properly, in dallas it goes from 25*-110*, sometime overnight...and can be very humid, then dry. FI obviously compensates for this automatically, how much tweaking will i have to do to keep it running right?

the motor is going to ollies for machine work, cross drill crank and grove crank, knife edge, boat tail, heat treat, polish, balance, ect... was going to use stock rods with arp rod bolts, any input here would be nice.

i would like to rev the engine to 7500, or even 8k if possible.

[herman maire]

stock rods ARE NOT GOING TO LAST AT THOSE RPMS's. In my opinion 7500 is about the max for a 3.6 .