steveelsbury

Hi Guys,

The TPIS Mini RAM kit comes with a new MAT sensor, which it says is to be relocated to the boot on the front of the TB. For this reason, it is mounted in a grommet to slot into a hole you cut in the boot.

Problem: I'm running a Vortech V1 blower, with nice, shiney *METAL* pipework to the TB.....plus, once the current upgrade is complete, I expect to be running 12 lbs of boost. If I drill the s/c to TB pipes and simply push-fit the grommet with the new MAT sensor, won't it simply pop-out again the first time I run up the boost?

If anyone could advise me I would be very grateful.

jburnett

I don't know why they did that... My MAT sensor is on the right side of the manifold (using one of the vacuum orifices) and I have it mounted to the fuel rail.
-Jeb Burnett
PS- You're gonna need bigger injectors...

steveelsbury

Hey Jeb - thanks for that. Having re-engaged my brain, I realise I did fit the old MAT sensor in the larger id hole in the ram (rear,left). It's just that having a replacement in the kit made me think it is an as-well-as rather then an instead-of. Think I'll email TIPS tech and ask them.

Bigger injectors? How much bigger? Better still, how do you work it out? Carroll Supercharging recommended the 36lb ones based on my engine spec. Of course, it wouldn't be the first time a company under-specified looking for repeat business? Any and all advice gratefully received.

TIA Steve

jburnett

I posted a handy equation in the Tech/Performance section under the injector thread...But, I'll tell you here instead. Here's the equation: HP x BSFC/# of cyls x Duty Cycle. So, with a 377 with 12 psi of boost I'm gonna say you're probably going to be looking at close to 650 horsepower. So, let's take that and run with it: Horsepower (650) multiplied by the Brake Specific Fuel Consumption (BSFC; which on a naturally aspirated EFI engine is about .45 but on a forced induction EFI is about .50) So: 650 x .50 = 325. Now, multiply the number of cylinders (8) by the injector's duty cycle (you don't want to go over about 85% or you'll wind up with some bad fuel delivery problems). So: 8 x .85 = 6.8. Now divide the 325 by the 6.8. 325/6.8 = 47.79. So, you need a 48 lb/hr injector to keep everything safe. Probably what Carroll did in suggesting the 36# is because they probably use a FMU (fuel management unit) that spikes fuel pressure when under max boost to essentially raise the lb/hr rating of the injector... This is basically the same theory that dry nitrous kit mfg's use and I don't like either one because it creates some potentially fatal (to the engine) problems. What happens when you hit an injector rated to flow at 43.5 psi with 80 or 90 psi of line pressure is you have the possibility of hydrostatic lock. That means the injectors either lock open or they lock closed; either of which will destroy your engine through detonation. The most common injectors to have this problem are the ball and pintle type (like Bosch, SVO, Accel) because the pintle is very susceptible to high pressure. The disk type injectors (like Lucas) are much less a problem because they are tested to a very high line pressure... Most of the guys running a lot of boost and high line pressures are using disk type injectors. Your best bet would be to size the injectors appropriately and then have the ECM pull pulsewidth out of the base fuel map when at no or low boost so you don't sacrifice drivability and fuel mileage...
-Jeb Burnett

steveelsbury

Wow Jeb - have I got some learning to do! Thank you very much for the information - my new injectors haven't shipped yet, so I have time to change the order!

You are probably right on the assumptions Carroll made, as they also recommended a Super FMU as you suggested, and twin fuel pumps - one replacement for the existing in-tank pump, and another in-line - both high volume pumps. They also said that the setup I was planning would require no ECM change, so it's all hanging together.

Clearly, I'd rather 'do it properly' - seems I'd better get myself an eprom burner too, as having to send back to the states for chip changes is gonna delay getting the setup right somewhat!

I'll get on the phone to them later and talk it through. I'll probably post more questions on the forum until I understand it all properly, but I'll do it under a more appropriate thread - this thread drifted off-topic a bit, didn't it? ;)

Thanks again, Steve

jburnett

Steve, you might want to check with MSD... They have some 50 lb/hr injectors that are high impedence for use with your stock computer system. Most injectors that are that big are low-impedence and require an aftermarket stand-alone like DFI, FAST, etc. However, Accel makes a piece that's very handy and allows you to use low-impedence injectors with a stock style OEM computer as well as giving you individual cylinder tuning capabilities. It's called a "VIC" or Variable Injector Controller. It allows fine tuning of up to 15% richer/leaner of each individual cylinder without having to have a full sequential set-up... You might want to look into that; I used one on a blown EFI 540" in a powerboat, worked GREAT with the blower!!
-Jeb Burnett

steveelsbury

Hey Jeb,

I ran your thoughts past Greg Carroll at Carroll Supercharging, and he had the following comments:

1. In his opinion, 'ball and pintle' injectors are more reliable then disc injectors (exact oposite of your opinion - nuthin's ever easy!)

2. The superFMU c/w 36 lb injectors, plus a replacement in-tank pump, and auxilliary in-line pump are the simplest way to go without upgrading to an aftermarket ECM. He says they have never seen a catastrophic failure on any engine they have built in this way due to injector lock, and in his opinion, it is the best way for me to go at the moment.

3. 50 lb injectors would be waaaay to big, because the stock ECM bank-fires once per cycle, as against sequentially.

I just read your post about the 'VIC' - Variable Injector Controller - and it looks interesting! Seems like it might be a cheaper alternative to an aftermarket ECM? It clearly answers Greg's point 4 too.

My problem (to pick one from the many I have!) is that I have now been given diametrically opposite opinions on this! Given that this is my first real taste of performance engineering (bolting the Supecharger on last year was no different to a grown-ups construction set!), I think I'll stick with the 36lb injectors for now, but I'll file away your algorithm and words about the VIC for the next stage - and you *know* there's gonna be a next stage :yesnod: Once I get my baby on the dyno, it'll all become clear.

If you think any of this is total bollocks, please let me know!

Many thanks for your input - this forum is great and I'm learning so much.

Had to do a last minute change to me header order today, because I suddenly realised I no longer need the EGR or AIR pipes on them! A major engine upgrade that makes the plumbing simpler can only be a good thing :)

Regards Steve

AKS Racing

I located the MAT sensor in the inlet side of the blower between the K&N and the compressor per advise from TPIS.

As for the injector issue, individuals such as TPIS and Formato (fasterproms.com) highly recommend against going with the larger injectors with a factory ECM. I too run the 36 #/hr injectors with a FMU and 11 psi boost. They advise that you cannot get a decent idle with the factory ECM with 50 #/hr injectors.

Best of Luck,
Aaron

jburnett

Hey, Greg builds the kits.... Follow his advice as I'm sure he'll warranty any misfortune. I just tend to disagree with him. As for ball and pintle and disk injectors, Hib Halverson wrote a pretty good deal about them awhile back; and I've never seen a disk type fail; on the contrary I've seen several pintle types fail when subjected to high pressures. But, like I said, Greg builds pretty good stuff, maybe he hasn't had a problem. In addition to domestics (specifically GM EFI stuff) I have quite a bit of experience with forced induction imports (yeah, yeah, I know...I hate em too) including a 9 second Mitsubishi Eclipse. I draw a lot of my forced induction info from these vehicles which some may say doesn't really correspond to domestics... But, I say BS, a motor's a motor, it's nothing but a big air pump and most of the physics between the two correlate. As for big injectors, what Greg told you is correct for the most part... However, if you'll reread my post you'll notice I said MSD makes some 50# injectors that are "high impedence" for use with your stock style ECM. If they were low impedence you would have to switch to either an aftermarket sequential computer or use the VIC. Everyone has different opinions on how stuff should be engineered and work; I just have a different opinion than Greg does and I have enough experience to conclude that my theories work pretty well. Greg may have the same experience with his methods. I submit this to you though: go find the really high horsepower forced induction cars (the strokers with the big huffers or hairdryers), ask them what set-up they're using with regards to EFI. The majority will be using big injectors and aftermarket computers or similar mods to the stock computer. At the very least tune the thing on a chassis dyno with a wide-band A/F meter and an EGT if possible.
-Jeb Burnett

black bart

I was told by TPIS that they can't burn a prom that will work on the GM computer at more than 550 hp. Greg I think Jeb is right if you look at my signature you will see that i'm doing what he has recomended I use a DFI and build the base fuel map to make it run right at all engine speeds and loads. Once you get the boost up your 36# injectors will be a little small but they should work ok for your current level of power if you do what carrol suggested. Good luck with your decision.

steveelsbury

Hey Jeb,

I did pick up on the high impedance 50 lb injector tip, but forgot to mention it in the reply. I didn't mean to 'diss' your opinion in any way, and everything you've said makes sense. However, given I am a performance newbie, I think it's safer if I stick with the Carroll recomendations for now. Greg did say after our little chat the other day that an aftermarket ECM was the next logical step for me, so we'll see how long those 36 lb injectors stay in my baby!

I'll start looking around for a dyno which offers wide-band A/F, and I'm fitting dual EGTs anyhow. When I fire her up for the first time, it'll be with the stock injectors pulled from the old lump - thought it might be best to sort basic timing first, before starting to throw the fuel in!

Spent the day polishing the a/c compressor mount, alternator, water pump and power sterring pump with a Dremel - buy do they shine now! I make no apologies for being a sad bastard!


Thanks for all your help.

Regards Steve

PS A 9 second Eclipse? You're kidding, right?
PS2 My wife keeps asking 'what's the point?' - like someone else said in their sig - you can sleep in your car, but you can't race your house!

steveelsbury

Black Bart,

Thanks for taking the time to reply - knowing someone else out there has been the same route gives me a comfort factor!

Different question: where did you get your triple pillar guage mount?

Cheers, Steve

black bart

Well they may make them now I don't know but about three years ago they didn't so I bought a double and a single had to do some triming to make them fit but I got lucky because they look like factory install. :cool:

steveelsbury

Hi Aaron,

Was the TPIS advice based on getting the MAT sensor out of the plenum which will be hotter? A couple of other people have just used the port on the left of the RAM behind the vacuum point, so I kinda went the same way. If it'll adversely affect anything, I'm gonna need to move it! Putting it between the K&N and the snail is the easiest option, as I can gust use a small silicon boot, and mount using the grommet?

Regards Steve

AKS Racing

I had wanted to move the MAT to in front of the intake to clean up the motor. I approached TPIS on the subject due to the blower, and they advised against any location with just the grommet. Either keep the factory unit, or move to a nonpressurized location, such as the inlet to the blower. Either way, the programming can adjust to the temps.

As for the comments on the large injectors vs. the small injectors and FMU, I have the following comments. I believe that the "ideal" way is to step up to the aftermarket computer (preferably FAST) and go with the large injectors. But if your cash supply does not allow the $2,000 investment for the wbO2 combo, than the FMU will compensate, but it still is inferior to the other route. My new project (larger stroker/blower) does include the FAST system w/wbO2.

As for the quoting of TPIS, they will consistantly state that TPIS will not tune over some level of HP with the factory ECM, but will advise you to speak with several others (Formato, Cronce, etc.) who are more than capable of handling the higher levels that are accomplished with stroker/blower combos.

Best of luck with your combo.

Aaron

jburnett

Jim Formato knew more than just about anyone when it came to OEM programming (God rest his soul)... Steve, no problem bud, I was neither offended nor upset. Everyone has his own opinion on how things 'should' operate. About a third of the time my opinion differs with others. I've used both methods of operation we are speaking of and I have simply made more reliable horsepower with fewer problems with the method I stated. The OEM computer, while actually more sophisticated than a great deal of the aftermarket programmable stuff, still has some serious limitations when you start throwing combinations like you're planning at it. You say you're going to run two EGT's, that's excellent. If you have flow numbers on your heads and if there's ANY deviation in flow between the ports (there shouldn't be, but sometimes there are); pick the cylinders that flow the most air to put the EGT's in... That way you're guaranteed that your readings are coming from the leanest cylinders and that'll keep the rest safe. If they are all matching closely (again, they 'should' be); put the EGT's in #7 and #8 as the back two cylinders always tend to be the leanest.
-Jeb Burnett

8388

I'm running a Haltech E6GM, with MSD 50lb injectores. the car did 570 at the rear wheels.The injectors under full load hit 80%. fuel pressure set at about 42 psi.

vette_tweak

Hi 8388...

I'm thinking of going the SC route and your setup would be similar to what I'm hoping to put together. How much boost did you run to make 570 RWHP? What CID is your motor? :cheers:

8388

Its a 6.3 liter, or a 383, at the time of the dyno it made 7 psi.