Re: 350 heads Thanks Bill. I have had very good results with 350 heads over the years. Have'nt done anywhere near as many as 455's. Even a 350 head in the 240 range is very good. The only down side to the 270 cfm stuff at this point is that the intake can't feed it, so alot of horsepower gets left on the table so to speak. Anyway, I do like the little 350's, I believe their day is yet to come. Jim Burek
Jim B., Just an update on our heads. We tried to tweak a little more out of the port runners looking for that magic 300. Not good results, we lost on the intake and picked nothing up on exhaust. 270/213. Still impressive but I know there is more there. It all seems to be in the bowl.:Brow: Now on to plan B. Where's my tub of epoxy! More to come...........
Bill, very interesting. Yeah, those little 350 heads are pretty impressive. I almost think much over 270 on the intake side will get into water. You are right about the bowl though. Jim Burek
I've been considering putting a blower on my 350 and I'd like to learn more about your project. What were the boost/HP/TQ numbers at 5500 RPM? I would never expect stock rods to live at 6800 RPM and if I can get the power I want at 5500, the engine will be that much cheaper to build. Have you done anymore work on this project?
As long as they are not cracked they are fine. You just want to plug the rocker holes if using later model rockers. Jim Burek
I think many of us would love to hear how it's going. However they want to be secretive it seems. :rant: I know either Tri Shield or PAE had some stronger rods made and may be able to do it again for around $1100 :shock:
No guys, not being secretive. I'm recovering from surgery at the moment and the project is on hold. My builder also has to finish about two dozen engines for other customers in the next few weeks. Racin' season is upon us!! I promise that I will post all details of this project from start to finish when the time comes. The reason I don't post the "during" results is so someone doesn't damage their engine due to incomplete info. It will come!!!! :Brow:
Pistons Light pistons are important for taking advantage of extra HP. Heavy stock and "cheap" forged pistons kill stock rods. At 5500, I can't see a problem with stock rods unless you start to push 6000-6200 but you better have a light piston if you want it to live. To get good power at 5500 is just a matter of getting the right pulley combination. Any time I have ever seen a Centrifugal supercharger run on a dyno, they have had progressive boost. SO, on a lower rpm, 6-8lbs of boost combination, you can use a standard "HP/Naturally aspirated" cam on say 110 LC since you don't want to hurt your bottom end power where you haven't built much boost yet. A few more degrees exhaust wouldn't hurt but I would keep the LC about 110. If you go 112-114 you can loose power unless you 'up" the boost to make it work. OR you can go with 112-114 on the low boost if your compression is a little high, say 9.5-10.5comp. This will help keep cylinder pressure down. Just as some info, I've seen combinations loose Hp on motor and keep the same loss on boost by dropping there compression form 10.0comp to 8.0 comp. It will allow you to run more boost without head gasket and detination issues but it can cost you HP across the board. This may not be the case with every combination. Cam, port volume/velocity, exhaust efficiency all play a part but if your not planning on over 10-12 lbs of boost, don't just automatically kill your compression. A lot of the same planning that used to go into putting a roots or screw type supercharger are being carried over into the Centrifugal superchager combinations and they don't work the same. Roots style superchargers build boost imediately. THis is all just something to think about. :TU:
Thanks for the info. :TU: I want to learn as much as I can about this. I checked out the xsperformance site and it all looks pretty logical to me. My goal is to smoke pretty much any stock vehicle out there and have some extra. I quit racing and my car won't be seen at the track but I definetly can't have some granny blowing me off a light with her new "less than 5 seconds" Caddy. Right now that could easily happen not to mention the GTO, the Mustang, the Vette and plenty of other fast cars on the roads these days. My neighbor has a Porshe Cayenne Turbo and I can't have him beating me either! I want 600 reliable HP. If I can do that with my 350 and a super charger I think I'll do it otherwise it's probably going to be a BBB. If a GN with a few mods can run 11's I can't see why my 350 Skylark with some boost can't do the same or better. By the way, the HP/TQ numbers for the 87 GN do not make sense with the way they accelerate. Those numbers must be underrated.
Been there, done that... Twice! With nitrous, 650 HP at 6200 RPM's is the exact moment of death! One of those engines sent a 15 pound piece of crankshaft with one rod still attached thru the pan, bounced off the floor and up onto a table 10 feet away!
re:350 heads Jim, This may sound stupid, but how are you changing the bowls? Sizing? polishing? Both? Are you using bigger valves than stock? Tell us more!!
The short answer, yes, yes and yes. DOn't really want to get way into details here, my experience with 350 heads is no where near as much as with 455 heads. There is still some learning curves going on here which takes time and money. I wish there were more really serious 350 people out there. Jim Burek
:grin: Im seriouse, lol, I have a '70 350, and so far i have Ported and polished heads, and brand new rebuild kit, and soon to come a Holly dominator carb, and D-1SC procahrger. All i want is a buick 350 supercharged, and intercooled.
i also want to know more i want to send my heads out to get bigger valves put in but dont know what size you guys are going, my uncle has been doing some port jobs himself but mostly just gasket matching but i still dont know what you are doing when you say you changing the bowls? can he attempt that himself. Rich
Sure he can attempt it himself, but if he does not have to a flow bench, he will have no idea on whether what he does hurts or helps. There is quite a bit to be gained in porting 350 heads, but make sure whoever does them knows what they are doing. Jim Burek
once again im not asking you to go into datail and explain everything to me but you just kind of answer a question with a yes or no answer and it doesnt help that much, no he dont have a flow bench so i guess we wont mess with the bowls because i dont even know what they are like I asked in the first post, but what i need to know is what size valves do i have the machine shop put in the heads for now. o No: Rich
Head flow.....until you get really serious, concentrate in the bowl and entryway into the bowl. Take material out around the guide and work on getting some air to the inside of the guide. Open up the bowl where the cut for the valve job ends and radius between the valve seat and floor if the port. But do not lower the floor in anyway or it will hurt your flow. For the intake port entry way, just square it off and clean up the casting on the rest of the port up to the bowl. Make sure you get a good valve job. :TU: 350T-type, Get rid of Or don't get that Dominator and get a carb for what boost you plan to run from CSU unless you know what you need to do to get a carb to handle AND work with boost. I know Bill seems to have had very good results with his carb from CSU and I think he even ran the TPC carb. Both were special built for boost. If you have never dealt with a boosted blow-thru before they are well worth there money over the headache of learning.
