cpfi or not to cpfi...That is the question

[IIR]

OK, I have a interesting dilemma..

I have been back and forth with projects from american muscle, to turbocharged rice burners. My last 2 projects were both subarus, both 400+whp AWD monsters and both more expensive to build than I feel nessesary. I lost my ass on both cars, and now I want american again, once and for all.

now please, stay with me, I will keep everyone up to date as I build my project truck and show you all every step of the way what Im doing, but right now I have a problem....

What engine am I best off using as my core engine to build?

My first choice is the 1993 Vortec CPFI engine found in the 93 blazer and Jimmy as well as Sonoma GT. Now this engine looks very appealing to me because of the appearance of the injection system, although it looks good, I am not so certain that its all its cracked up to be.

So my question is this, Am I choosing the right motor with a good enough injection system?

As far as internals go, Everything will be rebuilt and upgraded, Forged rods, pistons, polished and knifedged crank, block will be modded to use 4 bolt main bearing, New roller cam, lifters, rockers, yada yada...You get the picture. I plan on running this motor using mostly sy ty turbo manifold components and a custom air to air FMIC setup...All in my 90 2wd blazer.

Basically I would love to use a sy ty motor as a core instead, but the vortec heads and cost effectivness of the cpfi engine looks really appealing.

LMK

 

[supersports10]

here ya go .. all the info you need for your build, is right here.....

http://www.syty.net/phpBB2/viewtopic.php?t=38177&highlight=


on the cpfi... this is the WORST INJECTION SYSTEM KNOWN TO MAN!!
the supply lines are brittle plastic, the injector always goes bad, and the regulator always breaks,..nice looking intake, crappy injection system!
dont even mess with it, it only has one big injector in the middle of the intake, and it wont support the kind of hp levels that you want to acheve.

also th 96 and newer is a little better, but NOT ideal eathier
i have both systems, on two trucks, so i have first hand experience with both.

theres only three ways you wanna go...

1. complete sy/ty intake system, its the best you can get for a factory system.

2. modifyed edelbrock intake, for injectors. lotsa work here, but a quality system when you get done.

3. scratch built sheet metal intake, lotsa money, but high on the cool factor.

:2cents:

 

[IIR]

Ahhh,So the cpfi uses the same crappy "spider injector" setup. Thats disappointing.

Is there any source aside from getting lucky and finding a used sy ty intake setup that I can turn to?

This almost makes me think to use my TBI setup and pick up a injector plate from vortech or powerdine that has additional injectors.

Final thought, If I modify a edelbrock intake, what EMS would I use to run the injectors? Am I looking at full stand alone like a tec 3 which I am honestly trying to avoid after having gone thru that with my subaru's.

 

[supersports10]

a tbi setup would work, but you might wanna get the upper injectors unit from a 350-or a 454 there supposed to bolt on to the lower tbi unit, and be more # per hour.

i think 4.3 is a set of 44#

5.0 was 50#

5.7 was 55#

not sure on the 454 one i think its like 65# or more :2cents:

 

[ItsMyTy]

also... a '93 engine does NOT have the high flowing Vortec heads, even though it says VORTEC on the intake manifold. '96 was the start of the good vortecs

 

[SonomaGTlover]

on the cpfi... this is the WORST INJECTION SYSTEM KNOWN TO MAN!!
the supply lines are brittle plastic, the injector always goes bad, and the regulator always breaks,..nice looking intake, crappy injection system!
dont even mess with it, it only has one big injector in the middle of the intake, and it wont support the kind of hp levels that you want to acheve.

The CPI is not that bad... at least not IMO. It just needs help!!!
If you want a SyTy set-up and the CPI look... Why not convert the CPI to MPFI... I've seen it done before.
Just my :2cents: worth
I agree that the CPI injectors have ben known to go bad, but the new replacements are much better and more dependable.
I am in the middle of a CPI build now and it has potential. One of my sources for info is knockin on a 13.9 with stock block/heads and fuel delivery... low 12's on juice. I bet you didn't know that the injector is adjustable. You can get more fuel / air with minor mods and the stock cam is very close to the 412 upgrade that others talk about. There should be some decent flow with these mods and a decent exhaust.

Granted we're probably not talking 400HP but that's with the stock L35 (pre '96 vortec) heads. You'll probably want to use MPFI for the big numbers but I believe the CPI intake can flow quite well, if you can just get the fuel to flow. I don't know how much adjustment is available on the FPR but I do know that it can be increased. I am in the middle of upgrading to '96+ Vortec heads now and along with the other minor mods I'm hopeing to be in the 13's after some tuning. Haven't planned on the juice yet, considering some sort of turbo set-up. That decision will have to be made when I take out the stocker and build up the bottom end. For now it's Vortecs and minor mods.

You can see my pics HERE

 

[IIR]

Hmmm, OK, I hadn't considered the TBI option all that seriously till now. The fact that there are so many upgrades available for the Throttle body and well as inhectors cdoes make it seem very possible that it could work well. I noticed Holley even makes some nice setups and although the appearance of the TBI injection doesn't look like the smoothest and most effective type of injection and intake system available for a turbo setup, If it works I can live with it.

I am also aware of the lack of Vortec heads on my 90 tbi 4.3L engine, is there info available that will let me know if I can use them on the TBI4.3 or will I need to make similar modifications to the heads as I would if I was using a Sy Ty motor and intake?


SonomaGTlover : I read thru your buildup. Very impressive. N/A wopuld definitly still be a fun truck, but in my case, Once you go tuyrbo its hard to go back.

 

[dgoodhue]

Just my :2cents: If you planning on driving it on the street. A 2wd pickup and a turbo will be a burnout machine. My friend Syclone w/o the front drive shaft and just few mod (high 12's), could go sideways getting on the highway. Add in a bigger turbo and its only going to get worse.

 

[BigBadSmoosh]

CMPI sucks.

its the most powerful of the NA 4.3s but the central injector design is a POS.. plastic lines that carry your gas to the engine just doesn't sit well with me and I drive one everyday.

its a solid motor and im sure with some work it can go fast.. but i just don't see the benefit from that single central injector.. maybe converting it to fuel rails and seperate injectors would be a good route to take, it would be a sleeper.. you could probably hide everything in the intake and then just come up with a method of protecting everything from the air intake..

just seems like to much work for not much of a result.

 

[midnightbluS10]

haddixracing at s-series.org converted a CPI unit to run 6 injectors on a turbocharged S10

 

[IIR]

smaug : the suspension, and tire package I have planned should be sufficient for grip. Im planning on either 315-35-19 drag radials or R compounds on custom lightweight wheels I have sitting here. Im sure that much rubber on a over 4k lb truck should be pretty good.

BTW: I am beginning to lean towards the TBI idea. I have seen that holley makes some impressive TBI upgrades for this and have also heard there may be a intake manifold available that allows vortecs to bolt on.

 

[BigBadSmoosh]

smaug : the suspension, and tire package I have planned should be sufficient for grip. Im planning on either 315-35-19 drag radials or R compounds on custom lightweight wheels I have sitting here. Im sure that much rubber on a over 4k lb truck should be pretty good.

BTW: I am beginning to lean towards the TBI idea. I have seen that holley makes some impressive TBI upgrades for this and have also heard there may be a intake manifold available that allows vortecs to bolt on.

there is... one of the guys from MA has it.. converted it to 6 injectors..

 

[IIR]

Wait a sec...So he made or modified this manifold or purchased it done?

 

[442typhoondude]

Re: cpfi or not to cpfi...That is the question

I hate CPI's but not as much as the electric carburetor that people call TBI.
The later model CPI from 96+ had some of the bugs worked out. I wouldn't bother with the early CPI.

 

[Boosted]

Re: cpfi or not to cpfi...That is the question

lookup a guy by the name of Blazerguy on s-seriesforum.com.
He procharged a CPI when working for procharger. He even showed pictures of a CPI setup that he modified for 6 individual injectors, etc. He knows the CPI stuff in and out.. I think he even has the manifolds and supercharger, but I know the blazer is gone.....I think he got by with a FMU on the stock spider stuff, and it worked pretty well.....I vote for a go if you like what he has to say, as I think the layout of the intake, with forward facing intake is appealing, and would solve some of the issues of piping in turbo applications....

 

[vortecfiero]

Re: cpfi or not to cpfi...That is the question

i looked into modding my CPI as well... but it was a lot of bandaid or reinventing the wheel. plus with all the machineing and after market stuff.. it was way past my project budget.
I went Syclone set up and have never regretted it

 

[Try Me]

Re: cpfi or not to cpfi...That is the question

http://www.holley.com/HiOctn/ProdLine/Products/AMS/AMSM/9901-301.html

Dont know if anyone has used this. my vortec heads have been modified so the stock intake bolts up. I am going to be using my bowtie 18degree aluminum ones next year and was looking at this as a nice place to start. already has the injector bungs in it. you can get the "4barrell" looking throttle bodies in some insane cfm ratings that even have the place for you stock throttle and tranny throttling cables to hook up.

Anyone already done it? have pictures?