V8 swap headers

[Astro95]

So Calli V8: You used Thorley headers on your van right? Can you tell me what the part number was. I went to their website and saw they had a bunch of different numbers for Chevy pickups. Did the headers themselves fit okay? What did you have to do to the crossover pipe to make that fit?

I noticed that someone had a recommendation for using Flo Tech brand headers for AWD engine swaps. What was the part number for that? The reason I ask is that I live in California and I don't see a CARB exemption number for that brand which would make them smog legal. If I knew the part number or at least the application, then I could cross it to another brand that has the CARB exemption.

Thanks!

[blk lt awd]

sorry to take this off topic but what motor are u going with? i take it ure van is an awd as well?

[Astro95]

I don't consider that question to be off topic. My van is 2WD, but we have several AWD vans in our local junkyard. I was thinking to pick up an extra subframe and assemble everything ahead of time. I was thinking of a HT383 shortblock, World S/R Torquer iron heads and a LT4 hot cam with 1 5/8 in headers.

My thoughts are that the AWD system would spread out the massive torque of this engine somewhat to avoid breakage of drivetrain components and improve starting traction.

I love the idea of low profile, that is having an almost stock looking van that launches like a bear. I had a real pretty white Cadillac Seville with wire wheel covers and whitewall tires for many years. It was completely stock looking even under the hood, but had an Olds 403 and a built transaxle done by me. That was a fast car that handled just as well as it went because I beefed up the suspension with heavy duty springs, KYB shocks and Superlift airbags. I surprised a lot of people with that car!

[lockdoc]

The only problem with the AWD thought is the front diff that goes in these vans. I've broken both the diff and axles with the 4.3. So that is something to keep in mind if you build a high torque motor like you suggested. I must mention that I have a 4X4 transfer case so I have more torque going to the front diff. LS1AWD is running a stock LS1 engine for a few years with no problems so far with the front diff. ALSO I have converted a 2WD van to AWD before and it was a lot more work than originally planned. Lots of pieces needed from a donor van. I would give you a link to the swap but it apears to be missing at AS.com

[Mr_Roboto]

as much as there will be trial and error involved, I would try to find an alternative road to the FLowtechs on your van. The reason is that the primaries are very small and will choke a 383 especially with a pretty decent set of heads. Front diffs are another topic for another day, dependent on application. If he's in cali I"m not sure how much off roading he's gonna be doing, but it may be a street beast.

[lockdoc]

The primaries aren't that small. Same as most but with a thicker flange than most. It's the collector bell that is small. It has like a 2" diameter that can be modified for more.

[Rockwerx]

Astro 95, Not to rain on your parade or trying to discourage you, but there are couple of flaws to your plan (I have already tested your theroy...a few times! lol). It is very hard to find/fit a good set of headers into the AWD subframe. Also, with a high torque engine you will still break parts even when you "spread" the torque to two axles. The stock diffs and axles will only take so much abuse before they start breaking. The solution would be to install heavier diffs from a suitable donor vehicle. So if you are going that route, why not use a 2wd subframe (modify as required) as there is WAY more room to run many different types of headers.

Good luck with your project!

[Astro95]

Rockwerx: So what you are saying is that the even stock 2WD rear axle isn't strong enough to handle that much power? My van has the 7 and 5/8ths ring gear which I thought was the stronger of the two rear axles that were installed in Astro vans. I recently read a buildup article in Chevy High Performance magazine in which they stated that those axles are holding up well in Camaros. If that's the case, could it they grenade in Astro vans due to the extra weight?

[Rockwerx]

The stock diffs seem to take 350hp for quite awhile. More hp than that and they will break at some point. Given the extra weight of these vans, the rear diff is subject to a lot more stress than a Camaro diff. How many miles are on your diff? How much hp are you going for?

[Astro95]

I don't know how many miles are on my differential, but I don't think it's very many because when I bought it, it still had those little retainers on the wheel studs that hold the drums on during production and when I pulled the drums off, the rear shoes looked almost new.

I'm aiming for about 325 horsepower which will be about 260 at the rear wheels. I try to drive as smooth as possible. When I accelerate, I squeeze into the throttle instead of nailing it. When I brake, I try to never use them very hard either. I always get a lot of miles out of my vehicles before something needs servicing.

When I do the V8 conversion, I'm planning to pull the carrier and install an Auburn. I installed one for a friend on his four wheel drive truck and he was very impressed with it.

[Rockwerx]

I drive like you do...unless I am racing. Then it is pedal to the metal!

Your plan should work out well. Good luck!

[Astro95]

I got my engine finally. It's a 383 TBI crate motor from Smeding Performance. I lucked out and got the last one. Someone bought it, but never picked it up. They had paid extra to have it hot run and broken in on the dyno.

It's got an Edelbrock TBI intake and is supposed to put out between 270-310 HP depending on the exhaust system. Torque is 400 lbs ft between 2000 and 4000 RPM. They advertise it as 50 state smog legal due to the tiny 204/209 duration @ .050 and .412/.427 lift cam they put in. Their ad states that it works with the stock computer, but the guy told me I would need a different PROM chip.

I've decided to go with Thorley headers. From what I can tell, their THY383-Y2 should be the correct parts. It's for 95 2WD P/U with ABS and weld-on converter. I'm planning on looking at a few of those at the junkyard to determine exactly where the ABS box sits and the brake lines run on those.