V8 Conversion question.
 

Hello, I'm new to this site and am looking for my second 914 (first was 1.7L), daily driver is an '88 M3 - so I love the german cars & engines. But while considering a 6 for my next 914 project I came across some info on 350 chevy conversions - I don't really like the idea BUT I started thinking (and searching the net) why isn't anyone doing Ford V8 conversions as in Hipo 289 w/ cobra heads, high revving type engines that went into early GT40s and won LeMans (351,427) and beat Farrari. This seems more in keeping with the Porsche philosophy than a big block chevy. Those 289s would put out well over 350HP and would be a true 'roadrace' type engine that would love the higher revs. Now a Shelby 914 might do something for me and the engine parts would be relatively inexpensive (when compared to Porsche of the same HP) and easy to come by. Someone educate me, I must be leaving a few variable out of the equation.:confused:

I'd guess its a combination of simple case of economics and what the 1st few conversion companies felt comfortable with....

chevy's are normally cheaper to fix/hot rod compared to fords...

I have seen two Ford V8 conversions, one a 289 and one a 302....no one makes a complete "kit" which most people use to install a different motor. The adapter plate can be bought from Kennedy Engineering (for the ford, chevy and other motors) They do not sell kit's however, so if you want to do the Ford motor, you'll have to figure out the motor mounts and such yourself.

I'd buy the radiator from Renegade.........

Also, if I recall correctly, the Ford small block engine is longer than the Chevy. The Chevy will fit by moving everything back a couple of inches and removing the crank pulley. You run the alt. and water pump belts off of a grooved harmonic damper. Do all this and you still can't get you finger between the firewall and the front of the engine.

The only Ford I've seen installed had a hole cut in the firewall and the engine intruded into the passenger compartment.

If you want a small oversquare, high revving small block, build a 302 Chevy. If you can find a large journal DZ crank from a '69 Z28 (3" stroke) you can install it in a 350 block (4" bore) and end up with a 302. Or you can install a small journal 283 crank in a small journal 327 block (or so I have been told).

I also think the distributor is on the front end of the Ford. It will interfere with the firewall unless you cut holes for it.

The main reason for the SBC conversion? It's been done a buncha times; there's a lot of knowledge to draw upon.

--DD

I built a 240z datusn with a 400ci chevy, and the reason I chose chevy was because parts are cheap, and they are easier to make more power with than a ford. Also, motor mounts are pre-fabricated, taking out the r and d stage. I would HIGHLY reccomend an aluminum block for a 914 conversion. The best thing about a 914 is it's handling, you don't want to ruin it!! At a minimum buy aluminum heads and save yourself about 200 pounds.

I was wrong, I looked up my paperwork from when I built my motor, and I used aluminum heads and intake, and saved 125 pounds on my 400ci chevy. My bad, feels like more!! The intake manifold alone was a huge weight savings.

i think that more people should do v8 conversions with 928 motors....its a much better idea...keeping it in the family

and it is possible..although probably really hard and expensive

The SBF is somewhat lighter than the SBC, but as others have mentioned it is longer (by 1 to 1 1/4") the distributor is in the way, and the timing cover/waterpump mount is a problem. With a little engineering, these problems can be resolved if you're willing to go there. 283 crank (most are forged) in a small journal 327 block is a nice combination. A more modern option would be an LS1, but as in the case of the Ford, you'd have to do some engineering. 928? Weights more than an iron head SBC.

Andy

Yup. The motor is significantly longer than the SBC. You have to cut the firewall and move it forward--or cut the car in half and lengthen the engine bay!!

See this thread for a pic and a link to a few more pics of one such conversion in progress.

--DD

With the SBF 289 protruding into the cabin, wonder if it's so much as to make the passenger seat nonexistant or just moves it up a bit. There is quite a bit of leg room there as it is. I suppose the firewall could be reconfigured in that area, possibly even create an access panel from inside the car. Any thoughts on moving the engine back a little bit with trimming away some or all of the rear trunk area (and reinforcing it with a custom tube frame). That would make tuning the engine easier to. All comments appreciated.

First, the Chevy 350 is NOT a Big Block.

Secondly, the Chevy small block has been rated in "stock" form of 375 HP from a 327 (1965 Corvette), more than any production Ford 289 small-block.

Third, the Chevy small-block (302, and a basic small-block) used in Trans Am racing was so far superior to the 289/302 of Ford, that Ford developed the Boss 302 (different cylinder heads than a regular 289/302 engine) in an attempt to compete.

The Ford 427 engines used to beat Ferrari at Le Mans were Big Block ford engines (FE series) that had NOTHING in common with the 289/302 engines.

Chevy 427 engines were better than the Ford 427 engines. The Ford had the GT40 racecar and the Shelby Cobra, whereas Chevy pretty much had the Corvette (bigger and heavier than the Ford cars), but still fairly competative in most cases...

It seems that MOST Porsche owners that "bash" the idea of a Chevy conversion are not very knowledgable on the Chevy small-block...

The most popular reason for using the Chevy for the swap (besides the better fit) is the cost-per-HP ratio...

The weight is not much more than the Porsche 6-cylinder, especially when aluminum heads and intake are added.

It also seems that these people do not think the Chevy engine will rev very high (Presumably based on production passenger car engines-weak cam, etc). Sure, the 350 might not have the ideal stroke to be a high reving engine, but with light weight components (pistons and pins) and good balancing/machining, these engines will spin 9000+ RPM for hours on end (I don't care for Nascar, but have you ever seen a Nascar race or practice session where they show the tachometer? These guys run 355's (350's overbored)).

I have personally ridden in many "cheap" rebuild 327 and 302 combinations that easily spun past 7500-8000 RPMs without trick parts... And this was all 1960's technology...

Sure, maybe for a pure "race" car and possibly serious auto-crossers the extra weight will be a penalty, but for the street, the performance of the Chevy swap will far eclipse any Porsche combo (dollar-for-dollar)...

I took a trip to the recycle place today in my v8 914. They have a scale on the way in. The guy says that the scale is accurate to 80lbs.

I had a full tank of gas, 12 qts of used motor oil, and an intake from a truck, and my 150lb butt. Scale showed 2620lbs.

What does a stock '72 weigh?

I think between 2000 and 2100.

--DD

NASCAR engines typically redline at between 8000 and 8400 depending on the track. Maybe without the restrictor plates they could go a little higher but not much.
The only chevy small blocks I've seen that revved to 9000 rpm were installed in midget dirt track cars and they were all aluminium donovan engines, not really chevy. Nascar engines cost big bucks, I'm guessing $40k+,
donovan dirt track engines are about $25k. The life expectancy of these engines is measured in hours, not miles.

I built up an incredibly strong 327 about 20 years ago, couldn't get the valve train to live much past 7000 rpm very many times. Even with roller everything it is extemely hard to keep the valvetrain from floating above 7500 unless you replace everything with very lightweight titanium and unobtanium etc.

You just can't get valve springs to close fast enough with the heavy valve train parts and expect the parts to last very long.
I'm not saying 9000 rpm isn't possible, but I'd venture to say it isn't possible on a street engine that can go more than a few hundred miles between rebuilds unless someone is willing to throw jumbo sized buckets of money at it. We're talking cubic dollars here.
Who in his right mind would spend $50k on a CSB for a 914? Not me.
Mine cost under a grand :)
a small block can reliably rev to 6500 and not hurt itself with bolt on aftermarket parts. An engine like that should cost around $3500 tops if done right. Anything more is overkill IMO.

Noporsche, I should have mentioned in my original post how little I know about Chevy and Ford motors for that matter so sorry for calling it a Big Block. I wouldn't have a preference for Ford over Chevy except for the reputation that their roadracing programs have made, like sweeping the podium at LeMans 24h one year, etc. I just didn't think Chevy put much into developing such engines. The 289s and 427 did have something in common BTW, they both powered GT40s so Ford must of had a lot of confidence in their abilities. I'm not trying to build a GT40 so a hi-po 289 seems like an obvious choice (firewall blockage aside) to me. Hope I don't come across as a Chevy basher, Heck I'm very invious of Guy's engine - have you seen that thing, wow!

I had a V8 Vega with a 307 boat anchor. I revd' it till it sputtered (6500-7000) every day for 6 months. Then I pulled the motor cause the doors on teh Vega would not close :) . So I put it in my 69 Nova and drove it from NYC to VA 20 to 30 times. Mostly around 110 mph for 7 hours. Oh, did I mention that I paid 200 bucks for teh mojo? this story would not be possible with any other make of engine. The Nova now lives in VA beach running the same engine. I even told the guy the truth about that mojo

Sounds about right. If I subtract my tool kit and myself and the recycle stuff, I come to 2380 lbs race weight.

My rear wheels are probably about 60 - 70lbs each. and the fronts are 30 to 40.

My ricer whale tale has got to add a little in.

Does the fiberglass kit weigh more than the sheet metal that comes off?

I don't know about the RPM, but I'll bet you a cookie that the answer is, "It depends on what you mean by 'near stock'."

RPMs are an issue, even when not racing. Power is simply torque times RPM--making power at higher RPMs means you get to take advantage of shorter gearing and therefore you will accelerate faster.

So the faster you can spin the motor, the more power you will make. Assuming that you can actually make use of the extra RPMs by not having the torque curve drop straight to zero... Which is where the other boatload of money can go. (One to make it last at high revs, one to make the high revs actually useful.)

--DD

The Trans-Am comparison is of cars of the era. Chevy was the motor to beat for sure. Much has changed since then. Don't forget that at that time, the SBC had been a stable platform for years with lots of aftermarket and performance development. The SBf on the other hand, was in it's infancy of race/performance development. Fast forward to today, and you'll see far less disperaty. SBC crate ZZ4 350 = 355HP (fast burn 350 = 385HP). SBF crate 302 = 345HP (crate 351 = 385HP).

Andy

Guy - have you seen the video of my car on Renegade Hybrids web site? I think there is a shot of my tach. If I remember correctly I only blip it to 3 or 4 grand. But trust me when I say that it will hit the rev limiter (6k) in first (second on a stock car) in 1 second.
Second gear (3rd) is only good for another 2 sec. That is 60mph. I borrowed a g-tech meter and ran a 4.1 0 to 60 with a bad clutch.