Blower Motor Questions

[drewz28]

I'm rebuilding my LT1. Stock bore/stroke. Stock crank and rods. Forged pistons. 12 lbs of boost with a blower cam and nice set of heads. I'm shooting for 550-600 rwhp. What size injectors will i need? And what would you guys recommend for my heads? Thanks!

[impaladave]

I run 42# injectors on my set up. I am at 400rwhp and 435 tq. Th I am now in the process of doing a Walbro, Intercooler, and 12psi. I hope to get 500 rwhp with my 4L60E trans. My heads are stock iron ported, If you go with AFR ported or similar with a nice blower cam you should hit the numbers .
I hope you do, I'm going to have a similar setup.

By the way, are you intercooled, and are you lowering compression?

Here is a calculator for sizing
www.witchhunter.com/injectorcalc1.htm

Just my $.02,
Dave

[drewz28]

Yes, I am running 2 intercoolers. Not sure on the compression just yet. All depends on what I go with for heads and cam. I would like to get the static compression down to 9.5:1 or so.

[jdawgs94z]

sweet ride drew,keep us updated on the cars progress

['68SuperchargedLT1Camaro]

drewz28 said:

I'm rebuilding my LT1. Stock bore/stroke. Stock crank and rods. Forged pistons. 12 lbs of boost with a blower cam and nice set of heads. I'm shooting for 550-600 rwhp. What size injectors will i need? And what would you guys recommend for my heads? Thanks!

WELCOME ABOARD Drew! It's about time you got over here. ;D

First off, do you plan on using your factory PCM? This will let us know whether or not you can run very high capacity, low impedance injectors. Low impedance injectors, which are typically only used on race oriented vehicles, require more current than high impedance injectors. The injector drivers inside the stock PCM's can't handle this large current demand. If you plan on using the stock PCM, you are limited to using high impedance injectors unless you use an impedance converter which would allow you to run low impedance injectors. If your running an aftermarket fuel management setup like DFI or FAST, you can run either low or high impedance injectors. With all the demand for big injectors these days, large capacity (above 50 pounds per hour) high impedance injectors are starting to pop up. Here is a link to one site that I found that has 50 and 60 pound per hour high impedance injectors: www.ptrsds.com/injectors.htm What size injectors you'll need will depend on how much power you make, which will depend on your budget. That being said, I'm probably getting ahead of myself by talking about fuel injectors first.

Which supercharger and intercoolers are you using? This will play into how much power you'll be able to make.

As for cylinder heads, what's your budget? You could have your factory castings ported and rebuilt. There are plenty of guys who are able to get good flow numbers out of stock LT1 heads. I'm sure everyone has heard of Lloyd Elliot by now. He can port and rebuild your stock LT1 heads for about $1,300. This would include all the necessary machine work and all new parts. If you plan to get a pair of aftermarket cylinder heads like AFR's, plan on spending over $2,000. I believe the AFR LT1/LT4 195's are right around $1,900. You'll need to get some better springs, retainers, and locs, so expect to spends another $300 on top of that $1,900. Let us know what your budget is so we can help you decide on which way to go.

[Fire67]

Stock bore+stock stroke+boost=600rwhp???
I'd say its definitely possible, with some good flowing heads and around 15psi
What blower are you running?
For heads, I'd say some Lloyd Elliott heads like Rays would flow enough. AFR's definitely would flow plenty.
For injectors, I'll post up tomorrow with some calc's... Just dont have time today.

[94m6hardtopz]

i know a guy who ran 7s @ 3000lbs in a 10.5" tire car with a head that flowed under 300cfm and made over 1600hp. lloyds heads would be fine. when you're pump air down them they really dont care. the cam is going to be more application specific though. id run a lucas/delphi 42lb injector and race gas.

[94m6hardtopz]

i doubt the stock rods will live at 550-600rwhp, but they might. my buddy had a combo like that back in 98. it was a 9.0:1 compression 355" lt1, stock crank and rods, the heads flowed 260cfm, a little hr cam, a 4l60e and converter and an s-trim vortech making 12lbs. in this trim it made 490rwhp on pump gas. on drag radials with a 1.9 60' on the foot brake it went an 11.07@127 w/ the 3.42 gears in the 10 bolt @ a 3600lb race weight.

[Fire67]

I doubt the 42# injectors would support that kind of power. I havent done the calc's yet, but I know my Ford Motorsports 42.5# injectors are maxed out with 10psi on a completely stock(exhaust & S.C. only) motor.
I could raise the fuel pressure to increase the flow, but then I'd have to get the tune done again and probably max out my Walbro 255lph pump.
I'll try to get the calcs done this afternoon, but i might not have time...

[94m6hardtopz]

race gas will lower the BSFC, on the car that made 490rwhp thru the 4l60e we used motorsport 36s with a vortech FMU. we were running about 65lbs of FP. and that was without an intercooler. run a 2 or 3 core and the BSFC will drop even more. the vortech car had a 12.2:1 a/f.

[drewz28]

Thanks for all the inputs. Ok, here's my entire setup. The car is a 97 Z28. Completely stock at this point. The 4L60E is getting a full race build. The engine will have a stock bottom end but with forged dished pistons. The blower is a Procharger P1SC with twin intercoolers. I'll be running 12 lbs of boost. Stock computer, fuel system, 3.23 rear posi, suspension, etc. No weight reduction mods have been done. Honestly, I'll be happy with 500 rwhp. The cam I'm looking at right now is a 224/236 dur. with .530/.550 lift on a 114 lsa. It's a comp cams blower cam. As far as heads, I'm probably going to use my stock heads and just have a mild port job done on them. And then I'll have to match the injectors and stall converter to my application. The car's been down for about a year now, so I'm trying to do this as inexpensive as possible, but I am willing to spend money where I need to. And I'll be running 110 octane fully leaded gas in this thing. ;D

[1bad2k2ta]

drewz28 said:

Thanks for all the inputs. Ok, here's my entire setup. The car is a 97 Z28. Completely stock at this point. The 4L60E is getting a full race build. The engine will have a stock bottom end but with forged dished pistons. The blower is a Procharger P1SC with twin intercoolers. I'll be running 12 lbs of boost. Stock computer, fuel system, 3.23 rear posi, suspension, etc. No weight reduction mods have been done. Honestly, I'll be happy with 500 rwhp. The cam I'm looking at right now is a 224/236 dur. with .530/.550 lift on a 114 lsa. It's a comp cams blower cam. As far as heads, I'm probably going to use my stock heads and just have a mild port job done on them. And then I'll have to match the injectors and stall converter to my application. The car's been down for about a year now, so I'm trying to do this as inexpensive as possible, but I am willing to spend money where I need to. And I'll be running 110 octane fully leaded gas in this thing. ;D

Why leaded? You would be better off running 109 unleaded. If you run leaded gas, all your O2s will need to be widebands. Stock O2s will not last any time with leaded gas. You must not be planning on driving this on the street much and definitely not on trips.

If you are not going to forge the bottom end, you should at least use ARP rod bolts.

Why 12 psi on a P1SC? You could make the same power with a D1SC at about 9 psi at a lower duty cycle, and still have room to grow if you want to. High boost is hard on stuff; it is all about air flow, not pressure. If you are going to have your heads ported, you should talk to Brian at TEA (Total Engine Airflow) and see if they have a CNC program for Forced Induction on LT1 heads. They probably do. It has been stated on this board a few times already, and I will say it again, power is in the heads, whether you use a supercharger, turbo, N20, or N/A, but not all heads are the same. They can be optimized for specific applications. Check out the numbers in my sig. A s/c loves high flowing exhaust ports, preferrably 250+ cfm. Don't know if that is possible with LT1 heads, but Brian can tell you, if nobody on here knows. Here is a link to their LT1 heads:

totalengineairflow.com/products/gmhead/gmlt1/

Sorry, I get long winded when I am tired and it is pushing 3 am here and I took some Nyquil about 30 minutes ago. We can chat about this some more if you like, but in a nutshell, I did not want to wind the crap out of the motor to make power because I want it to last, and it isn't necessary to wind the motor. Just get the right cam/heads combo and pulley the s/c to make the power where you want it, and then don't over-rev it as you may push the s/c beyond its efficiency range, create too much heat and start detonating. Don't know if LT1s have a rev limiter, but if they do, you should set just a couple of hundred rpms above your shift point. I better quit, I feel like I am starting to ramble and this is too important.

[94m6hardtopz]

i would mix vp c12 (110 octane) and 93 octane in a 50/50 mix and run 42lb injectors. with a 50/50 mix your 02s will still last a long time. but the vp fuel guy told us not to mix anything above 110 ocatane. i have personally mixed c16 (117 octane) and 93 will no ill effects however.

[drewz28]

Yeah, I forgot about the O2's. I'll be running Denso O2's. They now have a "lead safe" oxygen sensor. I ran the 106 low lead on stock O2's and they took it Ok.

[drewz28]

Just out of curiosity, what kind of power do you think I can put down with 12 lbs of boost on a 9.5:1 compression with stock cam and stock heads slightly ported on the exhaust side? Think I can hit 500 hp at the wheels?

[94m6hardtopz]

maybe. probably closer to 450 on pump gas though.

[Fire67]

drewz28 said:

Just out of curiosity, what kind of power do you think I can put down with 12 lbs of boost on a 9.5:1 compression with stock cam and stock heads slightly ported on the exhaust side? Think I can hit 500 hp at the wheels?

I made 450/430 at the wheels with stock pistons (and compression), stock gasket matched heads, stock cam & valvetrain, full exhaust, 10psig from a D1-SC.

With everything but the blower and compression being the same, I dont think you'd get it. Especially with only 2 more psi out of a smaller blower.
In fact, I dont think 2psig will make up for the loss in compression.

Now with some easy porting to the heads and intake, and a nice blower cam, you should be able to get to 500hp.

[impaladave]

I think you will need to spray the motor with Alcohol. I am going with 12psi, Intercooled, 9.5:1 compression (maybe a little lower due to head work), through an automatic. I'm hoping for 500 at the wheels, but I've been dissappointed more than once at the dyno. I'm not sure if 12psi is too much for my compression, to stop detonation, the tuner may have to pull so much timing out that it negates the extra 2 psi.
I'll let you know how I make out next week, hopefully it's good news.

Just my $.02,

Dave

[Fire67]

impaladave said:

I think you will need to spray the motor with Alcohol. I am going with 12psi, Intercooled, 9.5:1 compression (maybe a little lower due to head work), through an automatic. I'm hoping for 500 at the wheels, but I've been dissappointed more than once at the dyno. I'm not sure if 12psi is too much for my compression, to stop detonation, the tuner may have to pull so much timing out that it negates the extra 2 psi.
I'll let you know how I make out next week, hopefully it's good news.

Just my $.02,

Dave

I know you have iron heads, but if my motor doesnt detonate at all on 10psi-intercooled with the factory 10.5:1 compression; I'd say you shouldnt have to worry about it...
Your goin intercooled and adding boost, plus your heads have been ported and you have an aftermarket cam... You shouldn't have a problem getting the 500hp mark at all. If you spray some alky you'd be able to run almost factory timing advance and probably be WELL over 500hp.

[impaladave]

I hope your right! I set my expectations low to minimize the dissapointment. I'll know next week, can't wait.

Thanks for the boost.

Dave

[Fire67]

Set your expectations high when choosing parts, set them low when they all go together and you'll always be happy with what you get

[impaladave]

I ended up with 501rwhp/560rwtq blowing through an unlocked converter in second gear.
Once I upgrade my converter, I think I'll hit 550rwhp, we didn't get to run it with the QTP electric cutouts open because it was flashing the 3000 converter to over 5000 rpm.

I am running 60# high impedance Mototron injectors, and could run it to 10:1 right to 6500 rpm. It is backed by a Walbro 255 intank, and a Holley 255 inline.

Also, remember that when you calculate the injector size, you need to think engine power. The Blower takes power to run, so the loss from the motor to the rear wheels is much worse than 15%-20%. If the blower takes 50-75 HP to run, then you have to add that to the RWHP number after the 15% drivetrain loss.


Dave

[Fire67]

See, you got your 500hp
So whens the Alky coming?