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.

Jay, I just watched your video. Heck, the sound was enough to get me off! You gotta tell me what headers/exhaust you're running with. Everything else for that matter. I just passed a milestone this evening - the first trial fit of my V8 into the car and it fit perfectly. I'm on a roll now. And going to be in the 70s this weekend - perfect!

I'd do a 327 Chevy or 350/383 anyday over a six conversion.... If you are gonna take the TIV out may as well get some real power that is cheap to do and basically is bulletproof...

I'd like to do a Buick V6 Turbo from a Grand National into a teener.... I think that would be a revvin animal!

here comes the cat...
problems with a 383 are that the 400 SBC crank is externally ballanced. Renegade sell$ an external counter weight and radiator. It is equally difficult to build a 383 with under 350/350 hp/tq, as it is to make the 901 survive under such conditions. the two factors mentioned above require high dollar system modification to handle los grandes Guevos.
Me and Rod Zappata from NY shoe stringed together a 71 914 over 13 yrs ago. I have been dreaming of build a nicer version ever since. it was a .060 over 350 with a tunnel ram and twin 650 double pumpers with a 4 inch spacer and a 3 hole fly catcher popping over the roll bar (no top in NY). the car was a filthy rusty turd, but that was before I knew what a 914 really was all about. I thought my 71 Camaro was way cooler on teh chic magnet scale. Man when that thing came alive in 3rd gear, it snapped ya back. 3500 was the magic number. the tranny lasted 4 glorious months and 2 not so stellar. The car and Rod moved to SD back in 91 or so. In 97 I met a man in Ocean Beach who had a 72 sleeper with a 383, Paxton centrifical compressor and a 250+ NOS shot. the bottle was mounted in teh cabin as an arm rest. He was running a G-50 with an oil pump and an ext cooler for teh tranny, shifted by a Patrick's Motorsports cable shifter. Years later he had it cherried out and up at Pomona for sale. That thing was the kind of car that you tape a $100 bill to the dash and tell people that if they can grab it before you shift, they can keep it.
oh back to earth now. I am building a 327 with AL roller rockers and light push rods. should go to 6500 with a grin. nothing else special. I dont pretend to know everything CHEVY but if you need to know something SBC, just ask (even historical crap)

the 68 302 z28 revd to 75k with ease. I love the way a grand nationals turbo comes on like a switch at around 3.5k

Hi. I'm very interested in this topic. I have a 72 914 roller chassis that I'm cleaning up for a SBC v8 conversion hopefully in the near future. I'd like to do Renegades"Open Budget" conversion, less the engine. I'd like to get a LS1 crate motor. My friends 99 Firebird has one. It's all aluminum. It has very smooth power. I'd like to keep the motor as light as possible. I'd like to keep the FI on the motor also. If I can't get that motor, then I'd like to get a 327 with aluminum heads.

Sean, my question to you is what kind of reinforcements are you doing to your chassis if any??. My chassis needs some work since the upper gap on the passenger side door is less than the opposite side. But I've checked for rust and haven't found any. It just seems like some sag. I'm sure that a chassis stiffening kit will be in order.

We'll see how it goes. This is my first 914. I've struggled with the decision of whether or not to do the v8 conversion. But then my vw's are not stock either. One has a turbo, and the other a T4. So why should the 914 be any different...Besides, I've always liked chevy v8 motors. And the 914 lends itself to it very nicely.

Keep the pictures coming Sean.


Thanks,

Eddie.

if it sags, it needs help regardless of engine size. Look deep under teh battery tray towards the firewall and under teh trailing edge of the doorn under teh rocker panel (passenger side). poke it with a pointed scribe. If it sags, you will find rust. Look at it from teh rear, dead-on. Does one tire lean in at teh top more than the other? This would indicate a compromised rear suspension console. a 914 will not twist up like my Vega did because the eng & transaxle are coupled.
I am installing the Porsche GT style kit and a roll cage....overkill
there is a guy named Brad from teh mid-west, he makes a 914 stiffening pc that runs from the rear suspension pick up to the front edge of eth rocker. May on this board have said it is a good way to go. I think its about 300 for both sides. I would do my car with his pcs if it sagged at teh passenger side door.

Guy - In the video I have an old set of Renegade headers and flowmaster muffs. I now just run headers and straight pipes out the back. It shoots solid flames at WOT and Pops side to side when downshifting. It looks like orange flash bulbs in my rear view at night. Fun stuff!

Actually I've got plenty of clearance between the firewall and the balancer/pulley. I'd estimate 1.5" but haven't measured it to be exact. This is with a motor-mount bar vertically aligning the SBC mounts with the original 914 bolt holes, and the balancer shimmed enough for clearance on the timing cover. Also, the old firewall pad stripped and covered with more modern sound insulation material.

Does everyone else with V8s have similar clearance on the front of the motor?

Maybe I should consider doing this so my wife will not want to drive it! I think she thinks I'm building this car for her.

My wife rode in my V8 914 once. I did a burst from a rolling start in second (sideways) to about 100 mph (of course it was on a closed road with a professional driver, don't try ths at home yada)
She had her hands covering her face and never climbed into it again :)
Was it something I did?

The G's you were pulling she probably couldn't get them off her face.

I have at least 2 inches clearance. Easy to change belts, but thats about it in the front.

I really like sleeper cars, but if you are going for shock value, nothing beats a heavy cam and straight pipes! My wife doesn't ride much in the car for obvious reasons, but the kids like getting dropped of at school once in a while. . .

I am working on shooting some video of the flame thrower to send to Renegades site, I was thinking of having someone follow in the bed of a pickup so they could get a good passing shot.

Jay,

Where is the 2" measured? Would that be to the rib on the lower part of the firewall from the dampener?

Andy

where is this video?

I just went and measured. . . If the pulley was next to the "Rib" at the bottom of the firewall it would have exactly 2".

But the bottom of the main pulley is about 4" above that rib and thus has 2 1/2 inchs of space. The waterpump belt does come really close to the shift linkage and probably hits it in at times. (tailshifter) but no problems in four years as a daily driver.

http://www.renegadehybrids.com/fun.htm

go down a little to my car (yellow 914)

It's not the greatest video, I shot it with a friend just goofing around, never thinking it would end up on the net. But the audio is kinda cool.

are you using the stock transmission? I have seen adapters to do that, although I don't imagine they would hold up to more than 200 hp or more?

The stock 901 transaxles don't care about horsepower, they care about torque.

The can usually handle up to 350 ft. lbs. of torque from a V8 without failing as long as 1st gear isn't used and the 2nd gear burnouts are kept to a minimum. I trashed mine very hard on the track and it never gave me a bit of problems behind a warmed over 350 chebby.

With a 6 they can't handle quite as much torque, or so I'm told.

What do you mean with a 6 they can't handle as much torque? Torque is torque, it doesn't matter. You just said that they don't care about horsepower. The reason that a 6 can make less torque and still trash the 901 is because they make more HORSEPOWER.

300 ft /pounds of torque divided by 8 power pulses is 12.5 ft/lbs less torque per pulse than a 6 cyl of similar output or 25% less