Inliners International Forums General Discussion Blown and Injected Turbo '71 Chevy Nova Build

wow that's pretty incredible, I wasn't aware that the motor came stock with steel sleeves! That's another indicator that the engineers at GM really took the time to build a quality motor! I did and still do plan on sleeving the block with Darton sleeves (I look at it as insurance as well as longer drivability). What would you recommend the as the limit to cylinder wall width? What are your cyclinder widths, and how much boost are you planning on running (what used to be 8psi) in the future once the build's finished?

I like you approach to installing the engine, checking diagnostics and tuning it before adding the turbo. That makes a lot of sense and would help determine what was wrong if indeed something was. I wish I could go to the tx convention, but I won't be able to get off work unfortunately. It'd be nice if it were in CA somewhere instead Be sure to bring up our topic of the 292 vs. the Vortec 4200 and tell me how it goes!

What would you recommend the as the limit to cylinder wall width? What are your cyclinder widths, and how much boost are you planning on running (what used to be 8psi) in the future once the build's finished?

Upto 8 PSI the stock setup is most likely fine right out of the box, use a conservative tune and go.

I run 94 octane pump gas, currently upto 11 psi. I would go more but am out of fuel (not enough injector). I think upto 15 psi should be fine on 94 octane and the low static compression. I rec'd some bad info on chamber volume when I ordered my pistons so I ended up with lower than expected CR.

My intake manifold is set up such that I can run a total of 3 injectors. 1 in the OEM position in the head, and 2 extra in each intake runner.

The stock location 1 is for pump gas, the other 2 are for alky. When the boost get over a to be determined level the gas injectors will shut down and the alky one will start up (with a blended area). Since methonal octane is about 130 fuel no longer becomes the limit on boost. The 4L70E (plus a lot of hard parts) will determine where I can get the boost to.

Currently plans are to goto 20 psi.

Sleeves

1) stay at stock bore otherwise you start having "fun" with head gaskets.
2) Darton Sleeve 0.1 to 0.12" wall, bore/hone the aluminum. Put the sleeves in as per Darton (.002/.004" interference fit if I remember right).

O-Ring the head.

So it definitly looks like we'll be making a custom intake manifold for the block (for insurance purposes and of course more boost)! As I mentioned before, we will be beefing up the internal with forged parts (rods and pistons) and will likely add a girdle as you mentioned. What type of girdle did you use, a one piece forged unit?

I am also from California where I believe the richest fuel is 91 octane (which sucks) but it'll have to do I guess. I suppose I could buy some of the products that supposidly boost the fuel's octane rating (bottles from Autozone, Pep Boys, etc.) but I'm not sure if this would be recommended...

As for pistons, any skirt design preferences or piston companies that seem to be with it? I hear good things about JE, Arias, and Wiseco but I definitly don't want some faulty info that'll effect my CR like you had to deal with! That's a bummer for sure! I'd like to go with Eagle rods (H-beam) b/c my dad has had great experience with them.

Since I will be running 91 octane, what do you think my max psi of boost will be w/ a 9.0:1 CR? I'm guessing around 8 psi? Also, how's the lag with your motor? Is that why you recommend running at least a 9.0:1 CR? Since there's only 1 fuel injector, did you already upgrade to a higher flowing injector? Also I think its really cool how you have 2 alky injectors to take over for gasoline. My dad says alky allows higher boost levels, but is also corrosive! I wouldn't want my expensive internals to be eaten by alky just to have more boost. What's your take on this? Also what do you think the motor will redline at? 6,000 is the peak HP spot on stock n/a motor with a redline at 6,250rpm; with beefed up internals do you think that will raise to ~7,000rpm for redline? Where's your power band at?

J&E has the piston design info for the 4200 e.g. head shape valve location etc.
The rod journal is larger than a SBC or BBC - if I remember off the top of my head 2.38". Eagle does not have a rod close to the right size.
The guys at black opel racing (BOR) orginally turned the crank in order to use SBC rods but ran into issues and on the rebuild kept the stock rod pin dia. and bought crower rods ( as did I).
The BOR have run the engine upto 8800 rpm with race cams and springs. The drag race guys go higher.

My power band peaks about 6800 and is done by 7200 - the motor has gone higher...

The stock injectors are about 23#/hr. Last year I ran 46# injectors and ran out of fuel... 63#'er are coming...

Methonal injection is widely used for knock supression under boost. google turbo mustangs these guys know turbo's and generally share info.

With EFI running 9:1 and 10-15 psi is fine as long as you have a safe tune up e.g. retard the timing with boost and be gentle leaning the motor out under boost. Adding water/methonal injection really helps - just rig up a system to limit boost if the water/methonal system is not working e.g. empty. This will prevent the ahhh s..ts from happening.

In Brazil they are running 100% methonal all the time in street cars - google methonal + material corrosion.

You can add xylene or toluene to raise octane,it's better & cheaper than those octane boost cans.
Here are the formulas:
http://www.gnttype.org/techarea/misc/octanebooster.html

MBHD

Thanks for the link Hank, looks like another route that'll let me run more boost w/o worrying about detonation

EFI-DIY,

You said '06 and up 4200's are better and '08-'09 4200's are boost friendly, so I'm trying to track down a motor ('08 or '09) but can't find any info on the motors and the differences between them or any upgrades made to the motors. Do you have a link or anything that houses this kind of info on the vortecs?