3.2 Rebuild time what should I do

Otis · 04-10-2009, 06:44 PM

Looks like my '88 911 will be needing a rebuild in the fall. If I am looking to improve performance on the track but still maintain it as a street car what should I do?
open it up to 3.4? standard rebuild with adding a turbo? Looking for some ideas.

vanwyk4257 · vanwyk4257's Garage

If you're buying new pistons & cylinders I would rebuild it as a 3.4 twin plug with slightly higher compression pistons, more aggressive cams with a Steve Wong custom chip to match. I have a friend with a similar setup and the car pulls like a freight train compared to my strong "stock" 3.2 in my '87. Check out the engine rebuild forum here, it will give you all the information you will ever need. Good luck with the project.

jcunning · 04-10-2009, 07:08 PM

I've also thought about this same thing. After some research, I think the best question to answer your dilemma is this:
How much horsepower to the wheels do you want?
Once you answer this question, everything else falls into place.

I'm not sure of the exact drivetrain losses, but 15% is a good round number I use. Maybe other members have the correct % for each type of tranny.

For me, I would like about 220 at the wheels. Taking into account the losses, I would need about 255 at the engine to achieve that.

Now you just need to gather the different options to get about 250 horsepower and compare the pros/cons.

For comparison, on the stock side of things a late year 3.2 outputs about 217 at the engine. Using 15% loss, that is about 185 at the wheels. So you would need to bump up power about 40 horse to get to 255.

I use at the wheel numbers because it is easier to verify with chassis dynos.

dfink · 04-10-2009, 07:34 PM

You said the "T" word so I assume budget is less of a concern than with some. That in mind it might be are you doing it yourself or paying. If you want streetable personally I think I would stay away from the turbo not that it wouldn't be driveable but just harder to work on for routine mainenance.
If you want power and cool do I what I did and go to a 3.4 actually 3.52 or close 10.5:1 compression. Twin plug, and for the cool electromotive TEC3r and PMO throttle bodies. Nothing quite like the look of a porsche engine with throttle bodies. Have the stock crank re-ground to a DC21 and pump out somewhere around 275 RWHP at 7000. Never gonna ping. You can program for whatever octane you want I use pump premium for the 275HP and you don't have any lag and you will never be tempted to bump up that boost just once to show the buddies. Cost not cheap but you may be able to do it yourself. Turbo you best have some equiment and fab skills. Or just regrind the cams, put on a sport muffler and a wong chip (which I happen to have for sale for your very application)
Unless trashed I bet you can get by with rings, cams, rockers, maybe chains of course then there is the clutch , flywheel, fluids, Don't forget to do the brake vacuum line while the tranny and engine are out, must clean the engine bay, Dang it those boots look kind of dry maybe while I have the engine out I should............................................ ..................

efhughes3 · efhughes3's Garage

Go over to the rebuild section here. Your same question has been asked more than a hundred times. Do a search and look at some of the suggestions that have been offered up, and the experiences of those that did what you will be doing.

Rebuild costs aren't for the faint of heart. Going to 3.4 with the other typical upgrades can easily get to the $mid-teens, even if you do it yourself. I spent almost $10k with no new P's and C's.

dfink · 04-10-2009, 08:29 PM

Yeppers........ Here is what I use as a figure. $100 a horse power that seems to work as a pretty good estimate. That is for increases you still have to figure the base of a rebuild.

JeremyD · JeremyD's Garage

I'm pretty happy with mine - 3.4 - still drives like a normal carrera around town - but put your foot in it a whoa - I still have stock motronic which was important to me.

Otis · 04-11-2009, 05:05 AM

Great suggestions, and thanks for the parts source plug as well. I do believe that I will be happy with just over a Horse per 10lbs at the wheels which sounds very achievable without adding the extra boost. Pricing the parts before I start seems relatively easy but sounds like some special( and somewhat expensive machining will be required. I would like to understand more about a cam regrind. sounds like you can't achieve any valve duration changes without out either a new cam or a regrind. Which would be better?

dfink · 04-11-2009, 05:05 AM

He is an idea if you want a challenge perhaps some pretty good gains but not that expensive to do.
Rebuild the engine keeping the original cylinders.
Replace the pistons with some 10.5:1 JE to get that extra kick.
Regrind the cam to 964 or better the DC21
Twin plug the heads (use pelican cgarr for excellent work at a fair price)
Keep the existing intake and fuel runners.
remove everything in front of the throttle body
Install 6 coils and use a megasquirt system to control it all.
If you want to save some money still twin plug just don't change the pistons.
I don't know if anyone has tried it but the car is setup for it with the individual injectors you could even use the distributor as the pickup for megasquirt. Just remove the cap and wires and put in a tooth whell and sensor.
Something a little different to have fun with, won't cost $15,000 to do it should get some significant gains in power and easily reversible if you don't like it or want to transfer it to another car.

dfink · 04-11-2009, 05:18 AM

Quote:

Originally Posted by Otis

Great suggestions, and thanks for the parts source plug as well. I do believe that I will be happy with just over a Horse per 10lbs at the wheels which sounds very achievable without adding the extra boost. Pricing the parts before I start seems relatively easy but sounds like some special( and somewhat expensive machining will be required. I would like to understand more about a cam regrind. sounds like you can't achieve any valve duration changes without out either a new cam or a regrind. Which would be better?

For street or mild racing you can have the cam reground. They can alter them a bit. Basically by shifting the base lobe of the cam they move the main lobe. Can't change them much but enough to make a difference. Cam grinding is not that expensive around $300 problem is if you grind the cam you have to reface the rockers to match the cam. That actually costs more than the cam regrind. After that you can go to any radical cam you want as long as you have a system to control it. Most cams past what they can regrind are going to be made for getting power up high for track use.

The machine work to twin plug is not that expensive considering it can save your engine from detonation. The twin plug itself adds little to HP but it allows you burn the fuel faster, which can allow for more advance which can lead to more power. subliminal message (use CGARR for heads and rockers)(go to webcam for the cams or some other cam place) (can no longer suggest DRcamshafts - sorry John)

The expensive stuff are the trottle bodies and an electromotive engine management system and the items needed to support them.

efhughes3 · efhughes3's Garage

Seriously, you need to go to the engine build section. The best guy, IMO, to go to for your cam needs and several other VERY experienced builders "live there". Besides, when you get going on this, you'll "live there" too. I did.

porschenut · 04-11-2009, 06:17 AM

Even rebuilding a stock 911 engine is quite challenging if you haven't done it before. Have you done it before?

Rebuilding and hot-rodding are two separate things. "Rebuilding" with 3.4 P/C's, wild cams, twin-plug, etc. is not rebuilding, it's hot-rodding. Gonna cost a hell of a lot more and require a hell of a lot more research to make sure you get something that works and is reliable.

efhughes, what on earth did you spend 10k on if you didn't buy new P/C's?

efhughes3 · efhughes3's Garage

Quote:

Originally Posted by porschenut

Even rebuilding a stock 911 engine is quite challenging if you haven't done it before. Have you done it before?

Rebuilding and hot-rodding are two separate things. "Rebuilding" with 3.4 P/C's, wild cams, twin-plug, etc. is not rebuilding, it's hot-rodding. Gonna cost a hell of a lot more and require a hell of a lot more research to make sure you get something that works and is reliable.

efhughes, what on earth did you spend 10k on if you didn't buy new P/C's?

Cams reground, rockers refurbed, complete head rebuild with Ti retainers and Aase springs, new bearings, timing chains, ramps, gaskets, new hardware throughout, Supertec studs, ARP rod bolts, resize-rebush rods, Ollies (the heads, clean/inspect/polish crank, clean/inspect case, inspect pistons & cylinders, machine down cylinders to alleviate some taper), new alternator, some cad plating, powder and ceramic coating, rings, new high pressure fuel lines, new crank sensors, "100 cans" of brake cleaner, misc sealants and chemicals, a couple of tools like rod bolt stretch gauge and a set of mics, and I'm sure a few other things that added up.

I opted to use Ollie's for machine work and I was in Texas, so there was $300 in UPS costs. I think the final total was $9600 or something, so in actuality it probably netted closer to $9K. I admit it, I didn't look for ways to save money, and spent more than someone looking to do a budget rebuild. But, once you open the case, you open Pandora's box, and the $ flow out of your bank account quickly.

Rot 911 · 04-11-2009, 07:35 AM

I drive my 3.2 alot and worried about getting high enough octane gas at times. So when I did my rebuild I stuck with the stock cylinders and pistons. Went with the 964 cams, SSI's and Steve W chip. Lost the rear bumper pads and all of the AC equipment. I'm happy, but it still wasn't cheap. Did it all myself except for John Walker rebuilding my heads. Still cost me around $7K and that was 5 years ago.

ericwitte · 04-11-2009, 08:01 AM

my euro 3.2 (10.5:1) has a flowed intake, 964 cams, SSI's, autothority MAF and chip (have to change to SW one of these days) and a lightened Patrick flywheel..dynos in high 230s...really fast and very driveable. The only option I would add would be the twin plugs, but even without I think you have an easy and manageable solution

dfink · 04-11-2009, 08:23 AM

Do a little and directly ask the questions you will find you can save a pretty good chunk of change using plain steel studs to replace the exhaust side on the heads. Unless you are going crazy HP the steel works. If you have the money go with the race springs but keep your money for the Ti retainers. Unless you are planning on some super RPM ranges they aren't going to really do much but they do sound cool and they probably make the vendors some profit. If they won't warranty the engine without them and you have the rev limiter set to 7000 or below find another builder. If you do a super over rev past what the springs can get closed in time the 4 grams of savings the Ti retains saved isn't likely to do much. The race spring won't do much for you on the street but they might, maybe, could possibly, perhaps save you on a slight down shift. For sure the ARP rod bolts. Get the green o-rings for the through bolts. Toss the gaskets that some in the kit and get some good silicone valve cover gaskets. I do not recommend powdercoating the fan. Can cause interference / fit problems. Sealing well that is an entire discussion on it's own. Also just because someone is thought to be the big guy or the little guy don't assume they are fantastic or lousy. I know for a fact the much of the work is farmed out so you don't know who in reality it is going to for the actual work. Good luck on your rebuild "Wild or Mild the bills will be Piled"
These are opinions gathered from my few engine builds they are only opinions and everyone knows what they say about opinions.

efhughes3 · efhughes3's Garage

Quote:

Originally Posted by dfink

Do a little and directly ask the questions you will find you can save a pretty good chunk of change using plain steel studs to replace the exhaust side on the heads. Unless you are going crazy HP the steel works.

If you have the money go with the race springs but keep your money for the Ti retainers. Unless you are planning on some super RPM ranges they aren't going to really do much but they do sound cool and they probably make the vendors some profit.
If you do a super over rev past what the springs can get closed in time the 4 grams of savings the Ti retains saved isn't likely to do much. The race spring won't do much for you on the street but they might, maybe, could possibly, perhaps save you on a slight down shift.

I do not recommend powdercoating the fan. Can cause interference / fit problems.

FWIW, the steel studs on my motor looked worse than the Dilavar.

I disagree on the springs. The reason I did my engine was due to a mis-shift. I think I caught it pretty quick, but still kissed all of my exhaust valves. The better springs will help avoid valve float. My goal was to make the engine as tolerant as possible to my idiocy, so it went beyond sounding cool or lining someone's pockets. If one is in so far on one of these, it doesn't make sense not to spend a few hundred more here. Such a mistake can happen on the track or a backroad.

I agree on not Powder coating the fan with regular powder coat. I had a Ceramic product done on mine. I kissed the edges of the fan blades with 150 grit paper, and had no interference whatsoever.

dfink · 04-11-2009, 10:55 AM

Quote:

Originally Posted by efhughes3

FWIW, the steel studs on my motor looked worse than the Dilavar.

I disagree on the springs. The reason I did my engine was due to a mis-shift. I think I caught it pretty quick, but still kissed all of my exhaust valves. The better springs will help avoid valve float. My goal was to make the engine as tolerant as possible to my idiocy, so it went beyond sounding cool or lining someone's pockets. If one is in so far on one of these, it doesn't make sense not to spend a few hundred more here. Such a mistake can happen on the track or a backroad.

I agree on not Powder coating the fan with regular powder coat. I had a Ceramic product done on mine. I kissed the edges of the fan blades with 150 grit paper, and had no interference whatsoever.

I think on the springs we are maybe saying the same thing. Put in the springs they may actually save an over-rev. My point was that I don't think you need to waste money on Ti retainers.

efhughes3 · efhughes3's Garage

Quote:

Originally Posted by dfink

I think on the springs we are maybe saying the same thing. Put in the springs they may actually save an over-rev. My point was that I don't think you need to waste money on Ti retainers.

I didn't weigh them, but it is amazing how heavy the stock retainers really are pretty "heavy" when you "palm" them. There is a fair amount of mass there that may work against you north of 7K. I really think that the Ti retainers, the springs and the ARP (or equivalent) rod bolts are cheap insurance, unless you really hose it up in RPM's.

cgarr · cgarr's Garage

Quote:

Originally Posted by efhughes3

I didn't weigh them, but it is amazing how heavy the stock retainers really are pretty "heavy" when you "palm" them. There is a fair amount of mass there that may work against you north of 7K. I really think that the Ti retainers, the springs and the ARP (or equivalent) rod bolts are cheap insurance, unless you really hose it up in RPM's.

Its always good to reduce valve weight but also take note if you are using Teflon valve seals the amount of additional drag compared to the Viton is huge.