Has anyone run 3.4 DOHC injectors on a 3500

[Mr.H.O]

Back in June I blew up my freshly swapped 3400 by misshifting at the track from 3rd at 6000rpm into 2nd instead of 4th. So I sat on it for about a week and weighed out my options and I decided that i'd dish out a little more and pick up the crank sensor relocate and trigger wheel kit and a fresh 3500.

I've got it in and it's running and has been running since but im running stock 3.1MPFI injectors and the 3400 upper plenum on the 3500 engine. It seems to run fine but it's been suggested to me to run 3.4 DOHC injectors.

I ordered the 65mm tb and adapter plate which i'll plant on the 3500 upper plenum. I guess my question would then be, Would using 3.4 DOHC injectors with the 3500 plenum and 65 mm tb on the 3500 with the 7730 ECM be a decent setup or should I be looking at other options.


I've also been looking at making the setup run OBD II but my only concern (and I havent got a straight answer for it) is how the OBD II ECM would react to the lack of input/output signals by having a manual trans instead of a auto trans.

[PCGUY112887]

If you went to OBDII, you would want a tuner (HPtuners or Powrtuner). With it, you could "tune out" your transmission. You would want a tuner anyways, the engine will run but not "well" without a tune.

Yes you can use the DOHC injectors in the 3500, I am using them with a newer 55psi FPR and my stock 96 fuel rail/lines.

Question - Why didn't you hit a rev limiter before the engine could blow?

[Superdave]

what would ever give you the idea that 16.5lb injectors from a 140 HP engine would power a 200+ HP 3500?

the 3500 comes stock with 24lb injectors.. If i was you i'd run the 24# DOHC injectors at 55 PSI to make them around 26-27lb/hr that should be fine if the heads are stock and you are using the stock cam.


you will need to tune it

[Mr.H.O]

This is exactly why i've contemplated going with an OBD II setup, to have a very user friendly way of tuning. I used to have some moates equipment but I couldnt ever get it to work properly so I just gave that idea up!.

Im unsure as to why the car didnt hit the rev limiter or if the 92 Beretta ECM that I am using even has one.What I do know is that when I took it apart to see what had happened I found myself looking at 6 pistons, all with 4 smiley faces on the tops of them! lol.

If you went to OBDII, you would want a tuner (HPtuners or Powrtuner). With it, you could "tune out" your transmission.
Question - Why didn't you hit a rev limiter before the engine could blow?

[Mr.H.O]

what would ever give you the idea that 16.5lb injectors from a 140 HP engine would power a 200+ HP 3500?

Well maybe the fact that they are currently doing so! lol. Im sure im losing out on some potential power from the 3500 and even the 3400 that was in there before. Funny enough the car still managed to pull 14.7 in the quarter consistantly with the exception of errors made by myself on certain passes.

Interestingly enough when I hook up the tech1 and run the car through various conditions it doesnt really ever run at a lean bias unless it's in decel or any other condition that demands it. Furthermore it also registers relatively clean on the dyno putting out readings that are all within spec for the 60degree engine.

[PCGUY112887]

Wait you ran a 14.7 on a stock 3500 with tiny injectors and no tune?

[IsaacHayes]

Uhm, rev limiter or not, if you are turning 6k RPM and then downshift, the engine is going to match the speed of the trans... You could have the engine OFF and it would still turn higher than 6k.... Engine braking is not affected by rev limiters. If the valves kissed the pistons, that means you floated the valves big time by over-revving when the engine matched the RPMs of the trans.

You should stick with OBD1. Swapping to OBDII will require a LOT of work, and you can get good tuning stuff such as the ostrich emulator for OBD1. It seems OBD1 might be easier to tune with too.

If you don't want to do the tuning, then get in touch with some of the v6z24.com guys, there are several on there that burn chips for 3400 swaps and could get you a decent "mail order" tune with those injectors and a tuning for the higher flow.

14.7 isn't bad but you could be low 14's with a tune, or in the 13's if you had a cam and headers.

EDIT: Assuming you are running a 282 getrag with stock V6 gears, 6000 RPM in 3rd is 89mph, then shifting into 2nd at 89mph would make the motor turn 9000 RPM!!!!!

[Superdave]

Well maybe the fact that they are currently doing so! lol. Im sure im losing out on some potential power from the 3500 and even the 3400 that was in there before. Funny enough the car still managed to pull 14.7 in the quarter consistantly with the exception of errors made by myself on certain passes.

Interestingly enough when I hook up the tech1 and run the car through various conditions it doesnt really ever run at a lean bias unless it's in decel or any other condition that demands it. Furthermore it also registers relatively clean on the dyno putting out readings that are all within spec for the 60degree engine.

I couldn't imagine them actually running the engine right.. maybe at cruse or with a light load but in PE Mode there is no way they could keep up. I bet your BLMs were getting pretty high.. probably running 15.x AFR's at WOT.


OBD 1 is the way to go, it's easy to tune with the right equipment.

[PCGUY112887]

Yeah my 3500 ran OK at cruise, was able to adjust it's self, but at WOT my wideband went off the chart for lean (over 18:1). Tuning is DEF required, one way or another.

[Mr.H.O]

Wait you ran a 14.7 on a stock 3500 with tiny injectors and no tune?

No I ran 14.7 on my stock 3400 with an intake and exhaust with 3.1 MPFI injectors and no tune!

Issac I actually have the ostrich emulator,aldl cable and strip cable but i've never been able to quite understand how to use everything to be honest. Everything has just been sitting in my basement for the longest time!

[91BerettaGT]

I thought you said you ran a 14.7 on a 3500 with 3.1 injectors, i was gonna be shocked, now that it's just a stock 3400 you ran a 14.7 i don't feel so bad LOL...

I also did the same. Once i made my Headers/manifolds though, my BLM's went through the roof and i then became extremely lean (as if i wasn't already)

I also ran a 14.55 @ 94. Stock 3400 on Stock chip cheap exhaust and CAI.

[Mr.H.O]

What are you running for injectors now?