V8 conversion question... fit / costs

[robphelan]

hey guys.. it's been years since I've been on the forum.. had to sell my 74 2.0l some years ago - apparent having babies prevents a person from spending any amount of time working on cars...

I've never fallen out of love with the 914, though.

Sooo, within the next year or two i'm going to pull the trigger on another 914. I was wondering if a Chevrolet 5.3L V8 would fit using one of the conversion kits?

I've owned, since new, a 2004 Chevy Silverado. It has about 98k miles on it and runs like almost like new. I only drive it a few times a month now - mainly to keep all the bits lubricated. I was thinking it would be a perfect donor motor. Or perhaps sell the truck and just buy a crate motor.

My plan is to pay someone to do it for me - I've hung up my wrenches b/c i'm not smart enough and I don't have the time to work on cars anymore.

Or, is it more cost effective to just purchase somebody's completed conversion? I'm not married to the idea of a V8. V6 would be fine.. it's just that I had the truck sitting on my hands.

Thanks for your advice,
Robert.

[Nostril Cheese]

Sell the truck and get a Subaru engine. Better swap all around.

[TheCabinetmaker]

Originally Posted by robphelan

hey guys.. it's been years since I've been on the forum.. had to sell my 74 2.0l some years ago - apparent having babies prevents a person from spending any amount of time working on cars...

I've never fallen out of love with the 914, though.

Sooo, within the next year or two i'm going to pull the trigger on another 914. I was wondering if a Chevrolet 5.3L V8 would fit using one of the conversion kits?

I've owned, since new, a 2004 Chevy Silverado. It has about 98k miles on it and runs like almost like new. I only drive it a few times a month now - mainly to keep all the bits lubricated. I was thinking it would be a perfect donor motor. Or perhaps sell the truck and just buy a crate motor.

My plan is to pay someone to do it for me - I've hung up my wrenches b/c i'm not smart enough and I don't have the time to work on cars anymore.

Or, is it more cost effective to just purchase somebody's completed conversion? I'm not married to the idea of a V8. V6 would be fine.. it's just that I had the truck sitting on my hands.

Thanks for your advice,
Robert.

Small blocks fit very well, although you may need to trim some of the rear firewall to clear some distributors. Some water pumps also can interfere with the front firewall, but you can either select a different pump or move the drive train back a small amount to clear.

I have a Buick V6 3.8 (231) motor, with headers, highraiser manifold and a 4160 carb. tons of torque, likely more than many Subaru motors. It is a real kick to drive, extremely quick. No clearance issues with firewalls, the distributor is on the front of the motor, not rear. Some folks even do a Turbo Buick V6 (grand National motor)

I have driven in other folks V8's and if they are built up are even faster than my built V6.

You may want to consider different gearing as the 914 stock gearing is designed for a motor that makes power at higher rpms than most V8's are built for, thus my Buick is a bit buzzy on the freeway, and I can start out in third gear. Often I drive it in 2nd, 4th and 5th gear and wish I had a 6th, it just runs out of gears so fast with all the torque One of these days maybe I will change the gearing. Use care with the tranny, burn outs can damage a stock tranny quick and first gear is very weak and easy to break, however except of putting around a parking lot, or start up on a col morning, I rarely ever use first gear. some folks lock out first so as to not risk breaking it, however first is nice to have for putting around and cold morning starts, just use some foot control so as to not break it. I prefer first to not be locked out for that reason.

Ideally you would like an aluminum motor to keep weight down, or at least get aluminum heads to keep the weight low, mine is all iron, but is still fun.

The fun V8 and V6 cars That I have driven all have hot-rodded motors, That is the way to go over a stock motor, as I think if you go to the trouble of conversion, you might as well hot rod the motor while your at it to take full advantage of your conversion. There is a lot of hotrod go fast parts for chevy's out here, many many options. real bullet proof motors too.

[Dave at Pelican Parts]

I think that the SBC motors are all pretty much dimensionally identical to each other. And since we know that some SBC motors fit, most or all of them should fit--if some of the accessories can be dealt with. Renegade Hybrids in Vegas has been doing these for decades, and knows their stuff. Much of their parts can be purchased through Pelican, though if you are having someone else do the work it would probably be best to go through that person. Or just ship the car to Renegade...

The axles, CVs, and transmission become very possible failure points when you start running V8 torque through them. There are solutions, but they can be somewhat costly. Or you can make sure that what you have is in good shape and then be careful about what you ask of the parts.

Dave is quite right about the gearing--Porsche doesn't even make a tall enough gear for the 914's gearbox that allows happy V8 freeway cruising. So a number of people will take something like an "H" gear and run it "backwards", flipping the drive gear and driven gear to the other shafts. Which, of course, is not free, and generally winds up being part of a transmission rebuild...

It can definitely be done, though. The problems are pretty well understood and there are solutions available. And there are other options, like the Scooby motor already mentioned.

--DD

[robphelan]

I faintly remember something about using a transmission from a donor 911 - which could withstand the torque.. is that the way to go? or rebuilding a 914 transmission & flipping those gears?

[Dave at Pelican Parts]

Options:
- 914 gearbox. Least expensive; you already have one. Can throw some $$ at it to strengthen and/or re-gear.
- 915 gearbox (from a 72-86 911). More expensive, but well understood. Ring and pinion flip needed, minimal machining required for that. New gear shift linkage and revised clutch linkage required. Mounts must be fabricated, or use Wevo's tail cone for mounts and shift linkage. More durable.
- 930 gearbox (from a ~77-86 911 Turbo). Only has four gears, but they're tall. Very durable. More expensive to buy, and requires more machining to flip the ring and pinion. Mounting and shifting solutions need to be fabricated.
- G50 gearbox (88-94 911). Must be flipped upside-down to run "backwards", I think. Requires modification to the oiling and breather setups. Better shifting than the above due to revised synchro design. More durable than the 915; not sure about the 930. Mounting and linkage must be fabricated.
- Boxster gearbox. Unknown torque capacity, a fair amount of modification to the chassis required to mount it. Starter fits on the "wrong" side, so provision must be made for that. Unknown clutch requirements. Evidently Boxster cable-shifter works well in a 914.

Take a look at the Renegade Hybrids site; they pretty much have this stuff well worked out.

--DD

[JEM]

i put a 2000 corvette ls1 in mine best thing is the modern efi and ignition starts and runs like a new corvette the ls1 is about 110 pounds lighter than an iron 350 sbc it is not a cheap conversion but well worth itmy engine is about 340 hp i am using a regeared 901 transmission


jerry