Chevy & GMC Vans

What made GM's Typhoon and Cyclones so fast? Was it just the turbo's? How extensive was the difference between that 4.3 and the Astro 4.3?

Has anyone "Cycloned" an Astro or is it more effective to go V8?

I realize that for my purposes, I want more torque, not a turbo.

http://youtube.com/watch?v=r9-xySskBCY&feature=related

Here are a little differences in the blocks.....
viewtopic.php?f=4&t=184

I figure one difference is the turbo, that's going to "boost" it a bunch. Remember the GN's of the mid 80's, faster than the vettes for a couple years and two less cyls. Another reason would be the AWD, you have to be able to be the extra HP to the gorund, all four wheels pulling helps. I think the heads flowed better, seems like I read some stuff about the motors on one of the S10 forums, but been a while. Would be very nice to have one!!!!!!! We have one member that has a turbo'd van, I had the video of his burnouts somewhere, just RWD though.

http://en.wikipedia.org/wiki/GMC_Typhoon
http://en.wikipedia.org/wiki/GMC_Syclone

what about doing an STS style set up with a rear mounted turbo vs. traditional.....we've got lot's of room under the vans and copying an STS truck kit shouldn't be all that bad.....of course this is just from a brief look.....has anyone ever thought about this and done further research?

The member who did the turbo mod was Ron from Texas. Ran well too!

Do a 60-1 T3/T4 hybrid with a .63 A/R turbine. If you can get the fuel system and engine management boost aware it'd be a decent setup, just mount the turbo right to the end of the Y-pipe. Besides that, the engine had nodular iron main caps, and special low compression pistons. Otherwise it was basicly a 145-155HP LB4 TBI engine, it used junk low flow swirl port heads and a tiny 179/195 duration TBI cam. Honestly, With the L35 cam or the "B" cam and L35 heads I think they could have made another 50-75hp fairly easily, but the 700R4 is only rated for 360 ft-lbs strangely enough what the Sy/Tys made. Even some stock ones can and do eat transmissions, the AWD/turbo 4.3L allow for killer launches however the trannies take a beating. Keep in mind these are like a 4X4 version of the 'vette trannies too, so they have the good parts in em. Besides this I also think that the turbo and intercooler are only marginal for a decent high powered 4.3L, and would much rather source a larger turbo and intercooler, preferably air to air for street use.

Don't forget that the Cyclone/Typhoon used significantly improved cylinder heads on those engines and different camshafts and aftercoolers as well. Bolting a turbo on your 4.3 won't come even close to those power levels. I would think that a V8 conversion would save a lot of $$ of that conversion.

wagonmaster wrote:Don't forget that the Cyclone/Typhoon used significantly improved cylinder heads on those engines and different camshafts and aftercoolers as well. Bolting a turbo on your 4.3 won't come even close to those power levels. I would think that a V8 conversion would save a lot of $$ of that conversion.

No, they didn't. They used standard LB4 TBI heads and a 179/195@.050 camshaft. A non-turbo/supercharged engine does not need an after cooler. A set of Vortec 4.3L heads way outflows the stock Sy/Ty heads and even the CPI heads are a common upgrade because they flow better.

Back in the day, I remember reading that the 4.3 Vortec heads were developed, at least partially, from the Cyclone/Typhoon heads...Not so??
Also, I recall these were turbo charged engines, with inter/after coolers.

what boost pressure were the typhoon's running? how much boost could a stock 4.3 block handle?

It depends on what is done to the block, with 4 bolt billet caps you could go single digits with enough boost, spray or turbo with something moderate weight (3000-3300 lbs) The crank is probably the bigger weakness than the block, I do not know if things have changed, but it used to be that you were talking a billet crank at about $2500 to have a fully forged bottom end.

There was a guy on S-series.org who ran in the high 9s with a stock block stock caps (all cast unlike the Syclones) but he had studs in the mains and H-beam rods with JE pistons. A Sy/Ty ran 15 PSI approximately and also had an 8.35:1 static compression ratio. Provided you have enough fuel for it (there's a lot of work there) you could probably run roughly 10 PSI on it, however I'd probably start at 7 and go up from there. This is on pump gasoline and intercooled probably, higher boost levels are capable with racing gasoline, methanol injection or liquid to air after coolers with an ice box.

Regardless unless you either put a 2 bar MAP on your ECU and subsequently add larger injectors/fuel pump, do an aftermarket EFI system like a Megasquirt, DFI or Commander 950 you'll frag it the first time you hit boost probably. The TBI systems have been used in a supercharged setup before, so it's not unheard of. Another option is to modify a carburetor for blow through put it on with an aftermarket intake and turbocharge that.

Syclone engine has 8.35:1 hyperutectic pistons on stock TBI rods with TBI crank, camshaft, etc. The pistons and the rods are the weak points. There are SAE papers that show that 4-bolt mains aren't required, but they do extend the life of the block.

The Turbo Buick engine doesn't have nearly as many head bolts, so you'll blow a head gasket before you kill the engine. The 4.3 had more head bolts. If you overboost or start to knock, you'll bend a rod or break a chunk off a piston. Been there... done that...

Or... if the original owner of your engine offset-ground your crank to get more stroke, you'll snap the crank in half Been there... done that...

I did see a 1st-gen Astro on ebay once with Syclone engine, but I haven't heard if/how it ran.

I put a turbo on my Astro, but I still have the stock compression ratio, so i can't run 15 lbs of boost

You asked T.......

dunedog wrote:You asked T.......

Ha, no doubt! Great replies, guys, lots of good info. Helps me a little with the direction I want to take my engine toward. Need more camping/off road stuff first.

Thanks.

Bring her up north one weekend with a V8 crate motor in the back and we will bolt it in and then you can drive home with the V6 in the back. Two people up here have engine hoists so that shouldn't be a problem. With your lift kit you might not even need to swap the oil pan.