3.6 long block rebuild advice please
 

Hello to all...I am hoping to find some expert advice on my next moves. I purchased a 3.6l 964 engine as a long block. Dropped it off to the rebuilder and he wants to know what my plan is for air, fuel and ignition.

The engine was already taken apart so we could look at all the parts and there did not seem to be any major issues. Piston and cylinders all reuseable.

I know these things can cost a fortune and the sky can be the limit as far as how much money you throw at it. I don't have an endless supply of money and want to keep the build reasonable...lol. It will be going in a RSR tribute so it needs to have some power but it will mostly be driven as a weekend touring car.

What is my best direction for the air, fuel and ignition...best bang for the buck. I dont think I want to go carbs....the wife probably won't be a fan....these are expensive decisions and the rebuilder needs answers from me before he gets too deep into this. Thanks in advance to any members that can help a new member out.

What is your budget? What are your HP goals? Assuming you want to run on 91 octane. So you want to go with EFI....do you want to go with ITBs? Who is going to tune the engine when done? What EFI systems are they familiar tuning with?

I don't really have a budget, but don't need or want to go over the top with this. The rebuilder is familiar with tuning most EFI systems. As far as ITBs....not sure...are they worth the extra money? For HP I would be happy with anywhere near the 300 make at the wheel.

What transmission are you putting behind this engine?

915 is the plan

If you want ~300HP at the wheels with a 915 you need ~350 HP at the crank. That's not easy for a pump gas street-based 3.6L engine.

I am a big fan an ITB setup using a MoTec M130 ECU with WeaponX CoP setup that Rasant sells. You can get it with a motorsports grade wiring harness which I think is the best way to go. Rasant has very nice ITBs but, for performance purposes, I prefer the AT Power ITBs. Rasants are nice because their ITBs are easier to setup for street use as they have idle air control (IAC).

I would call Rasant and see what kind of power their kits offer. They will have suggestions on cams too.

Thanks for the help. I will check out Rasant.

For street use most people want torque, for that,
102x109mm p/c set
and/or
vram
and/or
gearing
and/or
mlld cam upgrade
and/or
cat/bypass

here are some dyno runs for comparison

only the stock n-vram and '97 vram have cats, the 3.6RS is a stock '95 993 w/ cat bypass and 993RS cams, the 3.8 vram is w/ cat bypass , chip and 993tt sidemufflers
http://forums.pelicanparts.com/uploa...1646756840.gif

here's the difference cat bypass makes on stock motors w/ chips
http://forums.pelicanparts.com/uploa...1646756840.gif

here's the difference 102mm p/c set makes
http://forums.pelicanparts.com/uploa...1646756840.gif

I've built several 3.6 liter race engines over the years. All were 12.5:1 CR , GE 80 cams, ported....etc. All made roughly the same HP with slightly different induction and ECU's. 6 speed G50/20 trans, 319 RWHP or roughly 360 at the crank, and race fuel is required. I believe the early air cooled engines are capable of 100 HP per liter and that's pushing it. I think you should aim a little lower for a street car on pump gas. JMHO

Crazy question.... Anyone ever use a varioram but leave it open/no throttle body on top of ITBs?

Not that I have seen. There are a bunch of high performance builds out there using 996 GT3 Gen 2 intakes on top of ITBs.

a 915 wont survive long if driven hard and that kind of power.

I don't know…I have a active mag case 915 with all the right upgrades with a 3.6L race engine with 369HP/290Ft-Lbs torque at the wheels and the 915 is surviving fine. I am not being easy on it….

That was my initial plan and I have that intake already but lately I've become interested in learning more about the vram setup. Could be an option for the OP if he's a tinkerer.

VRAM has twin throttle body paths...so wonder if you could adapt an open filter element...if you would still get the vram effect.

I started liking the large single TB from GM that is drive-by-wire..and I think that would work great but you're not getting that extra tq from that setup like vram.

I would say that if varioram is not being used on race engines today, it probably is not going to make more power or improve drivability...I would stick with the 996 GT3 parts...

What's good for race engines doesn't always transfer to the street...I know, blasphemy! :) I will probably continue with the GT3 ITB setup but still keeping options open ;)

Do whatever it is you want to do….

Just bench racing……..

The main thing that vram does is raise lower rpm torque, the top ends # are quite similar
look at the 2 curves just above the bottom one, these are a 3.6 993 n-vram and a 3.6 993 vram
http://forums.pelicanparts.com/uploa...1646756840.gif



the 996 manifolds are closer in concept to the n vram manifolds as they both just use flaps to alter the resonance characteristics in the manifold by altering the volume and cross sectional area, the 964/993 version only uses 1 flap, the 996 up versions use 2 w/ a larger volume and larger cross sectional area appropriate for larger higher revving engines

the 993 vram has 1 flap like the 964/993 nvram version but also changes the length of the intake runners

The 996 GT3 intake setup is a single flap....I have one in my hand right now.

Sounds great for a street car. Hate to clobber this guys thread any more - maybe can tie it back to his desires a little. Does the varioram somewhat mitigate the poor OEM gearing for the street by providing that extra torque across the RPM band? It seems like it would.

both gearing and vram enhance torque available for acceleration but do that in different ways

short gearing enhances torque across the board, shorter tires or shorter cwp all the time and shorter individual gears while they are engaged

vram( length change of the intake tubes) enhances torque in all gears but only in the lower to mid rpm ranges

the variable geometry intake manifolds used in the 964/993/997/991/992 enhance torque somewhat unevenly across the full rev range

I just found out that the pistons are out of the required specs. New pistons are not cheap for these engines. I may have to shelf the intake upgrade for the moment. Is there any harm in using a used O.E intake, TB and twin plug on a rebuilt engine?