The V8 Conversion Thing

[dd74]

Hey again:

Read up on the V8 conversion offered by Renegade out in Vegas. Has anyone out there done such a conversion? How does the 911 perform with so much more weight inside the engine compartment? Is it worth it? Is the car spoiled in any way?

Thanks

[Jim Smolka]

A friend of mine has a V8 in his car (see 'Glad to have a V8').

It is possible, but the headaches are unreal. Cooling is a big issue. It can be done, but to be done correctly is not cheap.

IMHO, it is better to stick with the flat 6 powerplant.

[roGERK]

Hello dd

Here's a somewhat predjudiced reply to your questions:

Has anyone out there done such a conversion?

Oh yes, several people have. What's unknown is the number of idiots who have attempted this conversion and failed miserably. The occasional suspicious shed comes up on E-Bay, always with the engine missing or provided seperately.

How does the 911 perform with so much more weight inside the engine compartment?

It depends on what sort of lump of iron the idiot decides to use. Even when the weight is close to that of the flat six, the issue changes to that of centre of gravity - basically the flat six is (unsurprisingly) flat, whereas V8s tend to be quite high. Another question ole idiot probably never asks himself is that of oil surge - because of the engine position in a 911, the oil tends to get thrown violently from side to side during cornering in a way that engines mounted behind front wheels don't experience (at least to the same degree). Experience of this phenomenan in the 356s lead Porsche to use dry sump lubrication for the 911. Then there's a whole host of self inflicted problems concerning the transmission, gear-shift linkage etc etc etc.

Is it worth it?

Its probably the stupidest thing you can do to a 911 in terms of value for money. If the conversion is done very well (personally I've never come across one that is) then the value of the car falls by about 30%-60% that is (of course) assuming you can find an idiot who actually wants to buy it.

If the conversion is done badly, then the car is basically transformed into a source of spare parts. Either way, it isn't worth it.

Is the car spoiled in any way?

Its completely spoiled. If you believe (as Enzo Ferrari once said) that heart of a car is the engine, then the idiot just ripped the heart out. There are also handling issues due to centre of gravity and (usually) increased weight towards the rear of the car. The issue of cooling is critical, and the only "successful" conversions I've seen use a radiator mounted up front. This counteracts (somewhat) the extra weight in the rear. The problem then is you've moved from a low polar movement of inertia type design to a high-one - basically you've now got a weight on each end. That's good for straightline stability and constant radious curves, bad for sudden changes of direction and agility, areas in which the 911 traditionally excels. There's also a whole lot of issues regarding suspension changes, since the whole 911 setup is carefully designed to produce understeer at low speeds followed by progressive oversteer at higher speeds. Every vehicle manufacturer in the world spends millions of bucks and hours of laborious testing on suspension design and research. But ole' idiot reckons he can skip all that by fitting slightly thicker torsion bars and making a few guesstimated camber and toe-in changes. After all, what do them goddamn Krauts know about making a car handle?

In short, V8 conversions are done by idiots, or people who just love setting themselves mechancial challenges. If you're an idiot, go ahead and try it, if you like mechanical challenges, why not fit a steam turbine installation to your 911? You'd encounter thousands of difficult technical problems, waste thousands of hours of your life, and be able to spend $1000s devaluing your car. At least you'd end up with a unique vehicle that would provide endless amusement for all who saw it...

In short, don't do it.

- roGER

[czwbkx]

It is possible, but the headaches are unreal. Cooling is a big issue. It can be done, but to be done correctly is not cheap.

On the other hand, if you want to get over 300hp and gobs of torque out of a flat six...."It is possible, but the headaches are unreal. Cooling is a big issue. It can be done, but to be done correctly is not cheap."

Which leads us back to your original question. References to idiots aside, the post indicating that fore-aft relationship of weight is only part of the question is correct. Center of gravity is an issue if you're going to race DE or similar road-race events.

Wet sump push rod engines race successfully everywhere, so that's not an insurmountable problem. I'd think about TBI injection relative to fuel issues in a reverse-facing V8.

Scott has some good figures for relative mass of flat sixes and SBC V8s. It would be worth asking is these include aluminum heads. Then you have [a CG problem and] about fifty pounds. Remember that weight between the front and rear is shared in proportion to the relative distance. Trying to get enough mass out to counteract the fifty pounds should not be tough. The conversion moves the fuel tank toward the center of the car from stock location, so this will help. The radiator is aluminum and fairly low mass.

However, yep, it will screw-up the value of an otherwise high value car. So I would start with a low-value donor or tub. The work will be challenging, to be sure, and the results will depend on how you plan to drive. Don't plan on a lot of PCA events! But you will find plenty of other p-car owners who still think your car is damn cool with the conversion (comments on this board notwithstanding). I heard about one DE instructor driving a Renegade 911 on the owner's first event. His comment after a couple of laps was "holy $***, that's fast!"

Now, dd74, you and I will both have to change our log-on IDs if we want to stay on this board!

[JEB]

This should be good. I love these threads. Step back and let the fun begin.

Jeb
79 '930

PS: Somebody call V-8 George and the swampmonster

[Chuck Miller]

Had the dubious honor of driving the 2nd 'original conversion' back in 80'-81'. This car was a 66' 912 converted in late 69' by the Stanta Monica cop that started all this crazyness. (see: Car & Driver, Hot Rod, etc. - circa early 70's) BTW, the 1st car the guy did
was his own new 914. This 912 was maroon/red primer, had widened steel wheels, a '30 over' 283"/301" Corvette motor, with a 901 gear box. The North Hollywood owner had the car for over 15 years, having no less than 3 major wrecks, the last one life threatening (corkscrewing through the Santa Monica freeway/hwy 1 tunnel) His wife said enough IS enough about 1985.

My impression was ... it was fast as hell and handeled better then I expected. However I didn't drive it very long (up and down a fwy on and off ramp - just enough to stick my foot in it) AND I wasn't into driving fast Porsches back then.

I have to agree with what's already been said, it wasn't worth the effort... the car was dangrously unbalanced at it's limits ... AND there are plenty of Porsche powered hot rods AND stockers today, that would spank that old V8 car into yesterday - where it should stay.

Chuck

[Joeaksa]

CZWBKX,

Having some problems with your ideas here. Taking the fuel tank and moving it towards the center of the car would shift the CG (center of gravity) AFT, not forward. This would make the rear of the car feel even more heavy and not improve on the handling.

The only good part of this "arrangement" with the fuel tank is that I assume that its done to allow for the mounting of the radiator, and thus there would be another 20 pounds of water and such in front.

This would shift the CG forward but unless it equaled the excess weight of the V-8 it would still very interesting to drive through sharp corners at speed. I would prefer to watch from above....

Joe


>>>Trying to get enough mass out to counteract the fifty pounds should not be tough. The conversion moves the fuel tank toward the center of the car from stock location, so this will help. The radiator is aluminum and fairly low mass. >>>

[RarlyL8]

Gee, I'm glad ol' Fergy wasn't so narrow minded.
What kind of an "idiot" would put the engine BEHIND the rear wheels of a sports car?

The archives hold many a spirited commentary on this subject.
The bottom line? Depends on what you're going to do with the car. A simple hotrod made from a less expensive older 911 would be one hellofa lot of fun for a fraction of the cost of a turbo.

BTW - an aluminum head V8 weighs less than a 930 engine while making the same power, with no lag, for the price of a set of aftermarked stainless heat exchangers.

Economically, you'd be best off to buy a completed conversion and tweek it to suit your needs. Converted or modified cars (even 930's) never sell high enough to cover the costs incurred.

[mskar]

I find it best not to second guess engineers with a whole hell of a lot more experience than me, the designers of the 911 knew what the hell they were doing. You'll get your HP, but I'd bet the handling characteristics would be so screwed up you would run it into the wall. To me, a Porsche is not just about HP, its about balance and engineering... If you are looking to go really fast in a straight line, there are better platforms to start with.

[sammyg2]

Having built and raced a V8 conversion (in PCA santioned events), let me throw some info out here.
RarelyL8 hit the nail on the head, an iron block chevy SB with aluminum heads, manifold, and headers weighs less than a 930 motor, and just slightly more that a N/A 911 engine. If you go with an aluminum block, it would weigh even less. The higher center of gravity making a handling difference is pure bunk, just an urban myth. The CG may be moved slightly higher, but I really doubt anyone on this planet could tell the difference. The rear suspension will require stiffer t-bars, but that is mostly a function of the increased torque, and to a much lesser degree the weight.
A well done conversion will handle as good after the conversion as it did before. Period.

Water weighs about 8 lbs. per gallon, no way would there be 20 lbs of water in the front. More like 3 lbs. The radiators are aluminum and very light. The radiator in front will add just a little more weight than a big oil cooler would.

I really love the sound and feel of the 911 engine. It is much smoother that a chevy, and has better character. I would not take a good running six out to install an 8. That would not make sense to me.

But, if I had a 911 worth $10k that suddenly needed an engine overhaul, I would think twice before I spent $7k or more on a rebuild to get 200 hp. The price is just too high. For less money I could double that horesepower with a v-8. A $10k 911 with a blown up engine is not worth much. If you put in $7k or more for an engine rebuild, it is still only worth around $10k. The same car with a chevy will be worth almost as much, but won't take the $17k to get it there. So from that standpoint the conversion makes sense to me, in most others it does not. In that case, the owner would loose less money on a conversion than a conventional overhaul.

Cooling is not a big deal as long as you use the entire renegade kit.
I could do a 911 V-8 conversion in less that 40 hours if I had all the parts laid out and ready.

Oil surge is a very easy thing to control. How many 2002 model year cars available have dry sump lubrication?
A fully baffled oil pan for a chevy costs about as much as two oil changes on a 911.
I watched a race the other day and saw wet sumped corvettes litterally spanking 996 wet sumped Porsches. So much for the importance of dry sump lubrication.

I understand that the Corvettes are in a different class, that is not my point. The corvettes were running wet sumped small blocks and were much faster than the porsches on the track.

As far as calling others idiots for doing something I don't like, I don't play that game.
Roger, have you even driven one of these conversion cars?

[dd74]

I'm not too worried about changing log-ons because I ask the question of V8s in Porsches. With "value" thrown out of the equation, I still think the C/R (cost/ratio not compression/ratio) makes this a very valid query. After all, we are talking about a replacement for a stock 2.7 that, when it lets go -- if it lets go, can cost up to (as I've heard it) $10,000 or more to repair. Used motors (3.0s and 3.2s, even 3.6s) are a good bet, but they still are "a bet," aren't they, with possibly 10-grand and more invested? So that's why I'm doing the research, seeing what's what out there, putting out the feelers, etc., etc...

As for handling, I'm still not sure yet, but if a torsion bar issue is the only issue, 30mm and sport shocks should do the trick, right?

Still in all, a V8 should not be ruled out on what sounds a lot like proprietary reasons if there are possible allowances in the suspension, CG and other concerns. If I was concerned abour re-sale, I'd be dealing in junk bonds and body parts (human).

[Bobboloo]

If your really interested. There was a guy in Las Vegas that ran an ad in Pelicans Parts Used Parts for Sale board that was selling a 73' 911S V8 conversion project. The shell had already been modified to accept the conversion. He also had all the motor parts to do the job.

http://www.carletters.com/ebay/73_911/

[turbo dave]

Hey, I was thinking about doing a 935 Kremer K3 conversion, but with a Volkswagen turbo diesel. Looks fast, but with great fuel economy. Neat idea, huh guys?

Sorry, but asking Porsche guys to get excited about bastardizing their cars is kind of goofy, isn't it? Why don't we go to the Ferrari BB and suggest putting a flat 6 in a 308, or go to a Honda BB and suggest that a Toyota motor might improve the Type R. What kind of response do you expect? Sure, it might work- so what?

[H20911]

Just wanted to check with everyone to see if it is okay to modify my rear bumper (in progress). I never really liked the big rubber things but I don't want to seem like an idiot because I have never seen one done like this before and I hate to do something out of the norm.

[dd74]

As you said: Sorry, but asking Porsche guys to get excited about bastardizing their cars is kind of goofy, isn't it?

Shouldn't it be: "Sorry, but being a Porsche guy who bastardizes by going to Honda and Ferrari BBS sites is sort of goofy, isn't it?"

Yes, I think that's what you meant to say, though adhominems aren't really my style...

[Sean Hamilton]

Originally posted by H20911
Just wanted to check with everyone to see if it is okay to modify my rear bumper....I don't want to seem like an idiot .....I hate to do something out of the norm.

Well, If you must, but in their place I'd attach that tyre it's resting on.

[H20911]

I am just kidding around. I have always said do your own thing and do not worrie so much about what the other guy thinks. I was going to write about the conversion etc but I have before and this topic gets too old for me bother. I do like to see a spirited discussion though. I will try not to take the bait next time a newby asks the question.

[RarlyL8]

Hey aquaman - is that a Pirelli 345/35-15 that you're using for a workbench? Pretty jazzy for sutch a Gomer! Hahhahahah!

It's kindof goofy when folks get their panties in a bunch over an old crappy 911 with a blown 2.7L that has been saved from the boneyard by an adventurous hotrodder. That IS how most of these V8 swaps begin.

[cegerer]

A 'proper' V8 conversion would include a big block Rat motor in the front where it belongs!! Just imagine the big mailbox air scoop you could put on to cover it. THAT would be a true 911 hotrod. These rear-engine V8 conversions are mere child's play. -- Curt

[Porcupine]

I would think a Buick GN motor would be a good choice.
Compact lots of hop up parts. Parts are priced so a person can afford them.