I have a D1SC (not installed)...

I'm gathering parts for a new 350 build (not a 10k race motor, but something better than stock... and I have a few questions...

1st... is 15psi a good amount so my belt / pulley doesn't skip (I've heard of people having problems @ high boost) and without having to get engine 0 ringed for head gaskets and stuff ?

2n... Heads, I'm going aluminum, I know the chamber size will dictate compression at around 15 psi, is 9 or 8.8 good, why?

3. Do I want 1.5 rockers as stock or 1.6, why ?

4. I plan to get a specialized Cam too, any suggestions?

Thanks,

Raf

 

well 15psi would be fine, ideal compression would be 8:5 to 9:5, anymore you will have to pull boost out(underdrive) and/or intercool and/or methonal injection to stay out of detonation. alum heads are also a good choice, cause they dissapate deadly detonation heat better. for the belt slipping issue, they have cog style belts and pulleys if your worried about that. as for the cam, i would go with a custom ground chet herbert solid roller, built to match your combo. they are really nice, and very reasonable in price.

 

i have a d1sc (not installed YET too) i have heard that about the belt slippage can't comment till i get it in i'm using commetic MLS gaskets instead of the o ring style i had that but they say the MLS (mutli layer steel) is better u have to have a machine shop ring the heads 1.6 rockers will give you alil more power by openin and closing the valves more (bigger lift ) compression ratio you want low with that kinda boost if not if you have high compression its easy to detonate with that much compression and you can blow head gaskets or melt a piston custom cam i had a billet comp cams made they are very reasonable they helped me out a ton but it's all up to what to u just do alil reseach u should be fine good luck oh and get the bigger intercooler upgrade too

 

Not sure on belt slip, most guys with prochargers do get belt slip above 10psi sometimes even below do to the crappy tensioner setup. I actually got belt slip with an 8rib on my Procharger with a 3.7" pulley running an automatic custom tensioner making 8-9Ibs. As for compression on the motor shoot for 9:1 or 8.5:1 if you want a good amount of boost. You wouldnt need 1.6 rockers if you order the right speced cam that you need they just with add extra lift if your cam was too small for your liking. You wont need any fancy head gaskets i know at least for 12Ibs and below havent heard of anyone running that high with a stock motor that i can recall. As for the cam it doesnt have to be too wild but make sure the lobe separation is 114 or greater numerically preferably. Other than that as long as you have a safe tune on it the motor will be fine. If you do plan on that 15Ibs be careful with timing especially in the higher boost ranges itll need to be lowered a good amount.

 

1: 15psi worked well for me, and was the most the D-1SC could put out for my motor. I never had belt slip problems, but I was also always using belt lengths that were almost too short to even get on in the first place.

2: 15psi is reliable up to 8.5:1 compression without an intercooler or 9.5:1 with an intercooler. I'd personally go with the lower compression that lends room for intercooling and 24psi down the line(provided you have a blower capable of this). If you're at 9.5:1 compression with an intercooler, you're already maxed out other than some sort of injected power. The lower compression might be a little less fun on the street because it will more depend on boost for power, but as long as it's in boost all is good.

3: I'd go with either the rockers you have, or if you're buying new ones anyways go for 1.6's. Biggest thing would be to know the heads/springs are fine handling the extra movement.

4: I'd highly suggest a Bullet racing cam. I got a cam and spring setup from him that got me much better power over an already powerful combination. I guess this granted I did go a decent bit bigger size mechanical cam too.

 

I've been looking @ 350 engine blocks, bare and long blocks, new and remanufactured...

I found this company that has a 7 year warranty on remanufactured to OEM specs... If I get the corvette TPI (91 ?) it comes with aluminum heads & I could get a blower cam installed too for a smokin price... I do have a D1SC and intercooler...

http://www.chevy-350-engines.com/chevy-350-engines.html

They said they could customize it, just asked for price list (upgrade cam / pistons, etc...)

Raf

 

... as mentioned earlier, the problem stems from improper tensioner adjustment, not psi.

It's relatively the same, but whatever differences there are can be made up for in a variety of different ways, main one being in the cam specs themselves....

The duration of the exhaust valve in blower applications is a little more critical than it's lift, stay with the 1.5 rocker ratio....

They vary. Some guys insist on a little overlap, and some dismiss the idea. No one camshaft is really the be all end all for blower applications, and the people at ProCharger will tell you, they've seen incredible numbers made with camshafts that were far from being boost oriented. The idea is to maximize valve area curtain during the time of exhaust duration....

Gaspar

 

I've been checking Ebay and see some companies have rebuilt aluminum heads for $350 or so... which TPI / Vette / Aluminum ones should I be looking for? I read about casting 113, any others I should look for, or should I spend a little more and buy aftermarket?

I see the vette ones have small chambers (58cc), so to lower compression a bit I would need bigger or non flat pistons...

Raf

 

The guy at procharger told me that if you are building a motor to try and stay at 9 to 1 and that at 10 PSI there are fewer problems (sweet spot). I talked to Ed Wright (fastchip.com) and he said to get a cam with about 230 intake and 236 exhaust @50 duration and 112 lobe center. He said he has dynoed several and 114 will make a little more power up top but 112 will have more pop through the mid range. Ed also has a procharger on his camaro. The cam I ordered is 575 lift 230 236 @50 and 112 lobe center.