Tony

Jim, the wider the better on ourtype of intakes from what ive read. the TS tend to be more sensiive to inlet restrictions to flow than the CS set ups.

As for maximum duty cycle, im pretty sure you going to be running at 100% WOT, I was with 24#lb injectors, which is why you up the fuel pressures to increase the fuel flow at that point. Im really not sure about the mapping that the LH has for this....still trying to understand when it does or doesnt go to 100%

Jim_H

I thought I had seen a pic of the intake hose going where the alt. hose normally does but now I can't find the pic... Need to remember to take my meds...

BrianG

Tony, I am concerned for the service life of the injectors if we are exceeding design duty cycle limits. It's bad enough that we have all of those "relay, relay, relay" issues. I just want to understand whether we are tempting fate again.....

Bill Ball

In George Suennen's car, the intake, which I helped install, routes out under the passenger side fender in a space between it and the belly pan. I think it is 3", but Gretch can correct that.

Tony

Unless you remap things, i dont think there is much you can do.
You have to remember also, youre not at 100% duty , 100% of the time....

X amout of HP requires Y amount of fuel. No two ways about it.

There is a SC car out there putting 400rwhp out with stock 19lb injectors. Its at 100% duty im sure and has to utilize pretty high fuel pressures to get fuel but its working fine as far as i know?

Louie pointed me to this program. Kind of fun to play with.....

Jim_H

Below is something i posted from another thread and is from an EMS book. I read in another book that Bosch strongly advises against a duty cylce over 80%. I don't think there was ever a clear cut concensus on what this all meant.

They specifically discuss the Bosch pintle injectors but not in enough detail other than to warn against 85% dc and the problem of idling with the bigger injectors.
Fuel injector expert Russ Collins says injectors can begin to fibrillate at more than 80%dc causing fuel delivery to become nonlinear in fuel delivery and causing lean out problems.

Gretch

I don't know what the install looked like in george's car....his oil cooler is located differently than the 89GT. I do understand that required an alteration to Tim's design......My car has a 4" air intake routed from the drivers side fender.

Jim_H

It's 4", per Gretch.

Tony

Im not sure what a "pintle" on an injector is, but i think its the little protrusion that sticks out of the cap on the end, area where the fuel comes out? Dunno?
Both my 25lb and 30lb are the newer style that dont have that. just 3 or 4 small holes

Bill Ball

With George's 90 S4, the oil cooler blocked the driver side area. I know Tim provided George with a larger hose than originally at some point. Sure could be 4 inch.

It's hard to use the same route for a TS. Tim's kit replaces the fans and the intake hose routes from the head of the Vortec at the center of the radiator straight down and then off the the passenger side (in George's case). In the case of the TS, you have to navigate the radiator hoses on the pass side and the fan shroud unless you did some oddball routing around them or changed hoses and to a DEVEK fan shroud or some other fan arrangement. I have the DEVEK fan shroud, but the path still looks obstructed by hoses. Daryl's exit out the passenger fender by moving the coil and cutting a hole is an option.

We don't need 4 inches, do we? The intake path goes down to about 3 at the throttle housing and MAF, doesn't it?

Jim_H

There are pintle and disc. Ours are pintle. IIRC the disc are made by Lucas? Or maybe that is just another name for them.

http://images.google.com/imgres?imgu...lr%3D%26sa%3DN

DR

Hi Bill,

>We don't need 4 inches, do we?

I am not gonna touch that one :-)

> The intake path goes down to about 3 at the throttle housing and MAF, doesn't it?

MAF is 3.3444" (85mm) ID and 85-86 throttle body is approx 3.15" (80mm) ID.

If anyone needs one I have a custom calibrated 4" (104mm) ID 928 Super MAF.

Louie928

I found out an interesting bit of LH info while working with John Speake's Sharktuner. The shop manual and all other Bosch Motronic (LH) information I've read has the injectors batch fired at once per crank revolution. The LH switches to once per every other revolution injector firing at 5100 rpm. This is to allow for more time for the injector to stay open. The Sharktuner permits changing the RPM where this change from once per rev to once per 2 revs takes place. If you were to see your duty cycle getting higher than you want at the switchover point (5100), you could alter that RPM with the Sharktuner. I have 85% in my mind as the max recommended duty cycle. I might be wrong on that and it likely depends on injector design too. The duty cycle is probably more to worry about if max duty cycle is hit on a continuous basis than momentary. If you are setting up for a land speed record attempt, be concerned. If an occasional merge on to the freeway (we know we never street race), don't worry much.

Daryl

Bill,
Regarding the size of inlet pipe. There is a simple test to see if the inlet pipe is big enough. Corky Bells Supercharger book explains this. It's a matter of hooking up a vac gauge in front of the MAF. I will do this as soon as I can see some dry roads. Perhaps as eary as next week. My inlet pipe is 3 1/2" I.D.

Jim bailey - 928 International

Louis that is interesting switches at 5,100 RPM !