300 hp from my 95?

[sockjock]

So what kind of mods to engine and drivetrain would you recommend to get my 95 cpi 4wd Blazer up to around 275 HP naturally aspirated(non nitrous) and would I be streetable? I want to keep it a daily driver, but I want alot more oomph across the entire RPM range. I've done some bolt ons with little noticeable gains. I guess it's time to go internal. So help me out. I'd love to get 300 HP out of it but 275 would probably make me pretty happy too. I'm hoping to get another CPI motor to build up and when I get it completed swap out my current motor.

[Sparky2263]

Are you talking 275 at the crank or the wheels?

Also, streetable is a user definition. Hopefully, a lumpy as heck idle, high stall converter and the occasional phantom stall fits your definition of streetable. If not, 275-300 out of a 4.3 may not be realistic.

Or, pressure feed the engine. That's the easiest way.

[sockjock]

Well a lumpy idle wouldn't bother me. But I don't want too high of a stall. Like I said this is for a daily driver and 4wd so it would need to be driveable in bad weather too. I know I'm reaching for the moon with a naturally aspirated engine in streetable form but I had to ask. I guess I'm looking for 275 at the crank and maybe 250 at the wheels. Is this feesable with my daily driver requirements? What I'm looking for is something that is fun to drive: ie spirited driving, more highway power, and occasional runs at the track and a nice lopey idle would be nice. So far my bolt-ons haven't even come close to meeting my desires.

[sockjock]

Bump

[Sparky2263]

Gonna need a cam in the neighborhood of 280-290 advertised duration. Lift will be .500-525. Heads will need the exhaust opened up to 1.6" valves. The stock 1.94 intakes are fine. Stainless valves, good retainers and springs to match the cam will be necessary. Port matching the heads is a plus but don't get carried away with actually porting them. It can actually hurt more than it helps. Full length headers will be a must with free flowing true duals. An FMU will be needed to increase fuel delivery on the CPI along with a pressure gauge. A 3000 stall converter (won't stall that high behind a V6) will be necessary.

That should get you in the 1hp per cube at the crank bracket. Changing out the pistons to flat tops, zero decking the block and shaving the heads would increase compression a little over 1 point and probably bump you over 300 hp at the crank.

[sockjock]

How lopey would a 280 to 290 adv. duration cam be? Would this setup still be reliable as year round daily driver in my 4wd Blazer? Also would a 2 1/2" Y-pipe into a 3" single exhaust work? There isn't much room for true duals on these Blazers.

[rat]

A 280-290 duration cam is going to be very lopey on a 4.3. I would not put that motor in a heavy 4x4 either. You are going to give up a lot of low end. To make 250hp at the crank you will have to rev the motor to get it.

With a cam of this size a custom tune will deffinately be required. On a stock tune it will be pig rich at idle, and probably lean on top.

[sockjock]

So what kind of HP numbers could I expect from a 270 adv.dur. cam? And would this be more streetable?

[T Man]

To be streetable with a 4.3, start looking at lower numbers than 270. Rat has a pretty good cam in his truck with the 260, but even thats a littlte agressive.

[Sparky2263]

So what kind of HP numbers could I expect from a 270 adv.dur. cam? And would this be more streetable?

It depends on if you compliment it with re-working the cylinder heads and opening up the exhaust. The CPI is more than capable of providing the air and fuel in stock form, but the heads will hold you back with a cam change.

Small cam (260 or so), no headwork, open up the exhaust.......I'd say 210 to the wheels in good air. Maybe.

Ck. out my Free ET article also. Good CPI info there.

[sockjock]

Yeah I was talking about cam with headwork and slightly higher compression. Also I've read that the 260 cam is almost the same as the factory CPI cam. Is this true? In which case wouldn't the 266 be better and still good for a daily driver? I need some good info here before I spend money on parts just to find out it doesn't work for me.

[rat]

Yeah I was talking about cam with headwork and slightly higher compression. Also I've read that the 260 cam is almost the same as the factory CPI cam. Is this true? In which case wouldn't the 266 be better and still good for a daily driver? I need some good info here before I spend money on parts just to find out it doesn't work for me.
Yes, the 260 has fairly similar specs to the 260. The 266 would probably make a good cam with a stall converter.
Stock cam specs: http://www.s10planet.com/forum/showpost.php?p=44172&postcount=6

[Sparky2263]

Well, if you're gonna do the headwork and add the converter, why waste it on a small cam? Go ahead and move up to the 270-280 range. The stall will take care of any lower rpm loss issues and the hp increase will be fairly substantial.

Besides, the lumpy idle is a plus in my book. ;)

[sockjock]

If I moved up to the 270 what stall would I need with my 3.73 gears? And how would that combo do driving around town(35 mph) on the highway(55) interstate(70) and the occasional track run?

[T Man]

270 would pull like crazy on the highway, for stall, run about a 2200. If you run enough stall, you would be good all across the board, but dont expect to pick up any mileage from this.

[Sparky2263]

Stock stall is 2000-2200 (we use the Corvette converter). It won't stall that high because we have V6's and stall ratings are based on an average (whatever average is) V8. That's why I suggested a 3000 stall, it'll actually stall to 2400-2600 behind a V6. That's where a 270-280 cam will start coming in.

Around town you'd lose some mileage. Maybe 1-3 mpg depending on driving habits. 40 mph and up you'll still have lock-up, so no loss there.

My experience has been, after an engine performance increase, the first couple tanks of gas the mileage is horrendous. That's because of the fun factor though, not the engine. ;)

[sockjock]

So what kinda hp numbers should I expect w/head work(port match,mild port/polish,1.94int,1.60ex) and 270 cam w/ 3000 stall?

[Sparky2263]

I'd guess 220. Depends a lot on which cam, roller rockers, how well the heads are done.

Mine put 183 to the wheels with bone stock heads, stock CPI cam, full length headers and duals. I'd guess you'll be 40-50 hp over that.

[sockjock]

I've got another question for you. Putting my rebuild on a sideburner for now; could I simply install 1.6 ratio roller rockers on my engine with the stock cam and valve train and gain a slight boost in horsepower across the board? Would this require any other modifications or could I just install the rockers with the engine still installed in my Blazer and not pull the intake manifold or do any other machine work? Would this fit under my factory valve covers or would I need a valve cover spacer?

[rat]

For rockers...

You need 3/8" studs. You probably have 10mm studs, i would probably pop a cover to check though.

Full roller rockers like comp pro magnums and crane gold series or whatever they call them will not fit under plastic valve covers. You have to swap to the older metal ones, or the edelbrocks. The poly lock is where the problem lies.

Pushrod clearence should be checked where it comes through the head.

[Sparky2263]

The pushrods BARELY cleared on my 92 CPI. It's really close, but no rubbing.

The cheap and easy conversion is old style small block Chevy screw-in studs. They are 7/16" NC on the screw-in thread with a 3/8" NF stud. Use a 7/16" tap in the (already) 10MM holes. You will notice the tap doesn't quite clean up all the way through te 10MM holes. I pasted my threads with JB Weld and screwed them in. Tested tough to 6400 or so (wherever it was I managed to float the valves).

[sockjock]

Can this be done with the engine in my Blazer and doesn't someone make a valvecover spacer for my plastic factory valve covers?

[Sparky2263]

One of the guys on the S boards tried it with the plastic covers. Just flat out couldn't make it happen. Had to get the earlier steel ones.

[sockjock]

Don't the steel valve cover bolt up different than the plastic covers. Still need to know if the studs and rockers can be done w/ engine installed?

[Sparky2263]

No and yes.

[sockjock]

What kind of performance boost would you expect? 10 HP maybe?

[Sparky2263]

About that.

I started a new thread for this deal.

[sockjock]

So how difficult would it be to tap out the studs next to the firewall? I could unbolt the trans mount and jack up the tail shaft to tilt the engine forward some.

[Sparky2263]

It will be VERY hard. Next to impossible. You would be considered for a greatness award if you actually accomplished this.......

;)

[sockjock]

Ooh...I gotta have that award! Is it a big shiny one? You're not making this sound like something I want to try right now. Might just wait till I can find a rebuildable eng. and trans. Although the greatness award sounds pretty good.......I don't know if my bloody knuckles would be able to carry it.

[Sparky2263]

I was being very sarcastic. Took about 4 hours including the intake and exhaust removal. The holes are threaded all the way through the runners. Don't want the chips falling in there.

The biggest advantage is in having a fully adjustable valvetrain for future mods.

[sockjock]

Okay...sounds better. Did you already have headers? I've still got the stockers and I'd probably break some studs getting the exhaust loose with my luck. So it took you about 4 hours...okay I'll double that and add 2 more for a total of 10 hours.(I always take alot longer than planned) So it could be a doable Sat. project for me. ps Will my valve to piston clearance still be good with the factory pistons?

[Sparky2263]

Yes, already had headers. Piston to valve clearance is about a mile. Give or take a few feet.

;)