VH45DE Bigger injectors anyone done it?

[qsiguy]

I know there has been much discussion on this but have any of you actually installed larger injectors on your VH45DE? I'm diving into my plenum job this weekend amongst other things, and will be checking the injectors out thoroughly. If very many of them need replacement I would rather just get bigger ones since I will most likely need bigger ones anyway so I'm not maxing them out all the time.

If so, what sizes are available, type, etc?

[tmorgan4]

The nice thing is that all of the side-feed VG and SR aftermarket injectors (I'd probably stick with Deatschwerks or Nismo, some of the other brands are crap) are pretty much a direct replacement. You may need to get an adapter kit from Deatschwerks if it uses the oval connectors as opposed to the square ones.

[qsiguy]

So it looks like I'd need the adapter kit for $229, then I have several options.

I doubt I'll ever push it past 7-8 PSI so what injectors should I go with? According to Jeff Taylor the stock 370cc injectors can max out at 6 psi boost. I have the option of 450, 550, 650, 740, and 810cc injectors. Even with just the 450's I'm looking at $728 for the set w/adapters. ouch.

[tmorgan4]

That adapter kit was $229???? Damn....I do not remember paying that much for it. The good news is that it makes the new injectors fit perfectly. Very well made kit. It also included new pigtails for the different injector connections but I found it easier to just buy a nice condition harness with the right connectors.

The sheet I've got from Deatschwerks that I posted up a while ago showed that the 370s (which tested more like 410s for me) are good for 450hp when MAXED OUT. How much power are you planning on making?

[tmorgan4]

Another option to save yourself some money may be to just pick up a "phase 2" fuel rail and you won't have to get the adapter kit. I've still got the wiring pigtails if you don't go to a new harness. I asked Deatschwerks about this originally and there was something different about the different fuel rails that didn't clear the plenum (or something like that). Never tried it but I'm sure you could make it work with all the work you've done.

Keep an eye out on the classifieds here and on other sites. I see sets of 4 and 6 injectors all the time. It seems like the Nismo injectors are so closely matched that you could just pick up 2 sets of 4 and be fine.

[Florida240sx]

I've talked to deatschwerks and they will do and thye have some in stock to make whatever size you want.

[Stinky]

What are you going to do about the ecu? Keep in mind you'll need to reprogram it to account for the extra fuel.

[darinz]

My truck has been dynoed with 375hp a the wheels and has standard injectors. It is running 10psi (and avgas) and it is estimated that he flywheel hp is about 530. It is limited to 6000rpm due to wastegate size ie a bit small and getting creep above that and also the injectors are at 87% at 6000rpm. So if you are only running 7 psi what is the need for bigger injectors?I'm running an Autronic ecu and CDI so I guess I have more acurate tune but still I don't see any reason why you need to run bigger injectors at that low boost.

[qsiguy]

First of all, I completed the plenum job and all the injectors tested at 11.5 ohms so I left them. Reason I was/am concerned about maxing them was that Jeff Taylor claimed he was at 100% duty cycle at 6 PSI. I personally need to do a few more tests and data logs to be sure where I'm at. I've noticed I'm at about 80% duty cycle at around 6k rpm but they do keep rising exponentially after 6k and my redline is set for 7k currently. Still need more tuning and testing.

At 6 PSI boost above 3.5K my AFR's are in the mid/low 11's. Where are your AFR's darinz? If I'm getting close to 90-100% duty I guess it would be safe to increase the AFR to the high 11's/low 12's. I'd just prefer to be on the safe side.

Here's a screenshot of one run last night.

A bit more tuning and I should be ready to get another dyno done and really see where I'm at.

What are you going to do about the ecu? Keep in mind you'll need to reprogram it to account for the extra fuel.

I've got a re-chipped OEM ECU and all the software to tune it.

[tmorgan4]

There are a lot of very good tuning articles out there if you look. Here's a couple that I've saved. The first one is an article about how to tune your Megasquirt ECU but just ignore that and read the part about tuning. I did question a few things I read on that first link (it seems to encourage a lean/almost stoic mixture on certain conditions when accelerating) but I don't know enough to say whether or not it's wrong.

http://www.diyautotune.com/tec...s.htm

http://www.max-boost.co.uk/max...r.htm

And a little turbo specific tuning......

http://innovatemotorsports.com/resources/rich.php

By the way...what are you using to tune the factory ECU?

[qsiguy]

Thanks for the articles. I've done quite a bit of reading over the last year but I'll always read more. Here is a link to a great article I got a lot from.http://eccs.hybridka.com/viewtopic.php?f=19&t=47

Currently I have a '93 ECU that has the EPROM removed and a ZIF socket inst. I have a bunch of stock and sample tunes for the VH45DE and I primarily use Tunerpro to modify the bins. I can also use Romeditor to modify the bins.

[rhinoone]

In order to use the 93 ECU, did you change the harness to a 93, or just plug it into the 94 harness?

[qsiguy]

It's plug and play. They are cross compatible and everything works fine. I think there is an issue with the secondary cooling fan when using the older ECU but it's never been an issue for me.

[Jeff Taylor]

Like qsiguy said, my injectors are currently maxed out at 100% duty cycle and MAF voltage is railed at 5.0 V. This is at 6psi of boost on a Garrett TV7512 turbo (72mm) running at air/fuel ratios of around 12.0:1, with a Walbro 255HP in-tank pump running on the stock VH45DE fuel pressure regulator.

This setup, on 93 octane, made 446wheel-HP on the dyno several months ago.

Anyway, I am upgrading my fuel system as well, but I am machining a rail to accept top-feed injectors and am placing them in the stock location. I am experimenting with the idea of countersinking the injectors deeper into the runners to allow for enough clearance above the top-feed fuel rail.

I'll see how it all works out soon.

[darinz]

I'm not sure of the AFR's but it was tuned to be safe rather than to have max hp. I'm running 100 octane avgas but the real advantage is consistant quality that pump gas just doesn't have. Sometime soon I'm going back on the dyno and will get maps done to allow lower boost and pump gas to be used as sometimes it is a pain having to get fuel from an airfield if I'm racing awayfrom home. To do this I think I'll need bigger injectors as the tuner thinks he'll need a lot more fuel to control detonation. At present the fuel quality means that isn't an issue. He just set te AFR's then advanced the timing untill it detonated then brought it back slightly. Then I can just run the map to suit where and wha I'm doing. The joys of a USB conection to the ECU.Sorry I'm not more help but the exact figures weren't really important to me.

I'm pretty keen to be able to run top feed so keep us informed about the countersinking etc as that is easier than spacing the manifold up. I have plenty of room above the motor to do this but would rather keep it standard.

[qsiguy]

I forgot you were using 100 octane. I ran 1/2 tank of 100 octane racing fuel and even with the stock tune it didn't detonate at about 5 psi. Our pump gas is only 91 octane at best until you jump to racing fuel for almost double the price. Our 100LL avgas isn't an option due to the lead content since I still have cats on mine.

A couple nights ago I tried a tune and it worked pretty good but I tweaked it some more and just got to try it tonight and it was awesome. I also did a datalog so I could see where my injector duty cycle and MAF were. According to my latest findings I should be able to take it up to 7 or 8 psi quite easily. At about 6.5 psi boost, 6850 rpm WOT, both banks of injectors were at 82% duty cycle and the MAF was at 4.78 volts. AFR at that point was about 11.2 so I could increase that a little and still be safe. I think I can get it to 7 with no trouble at all and probably 8 psi.

For this latest tune I moved the injector K value back to stock of 198 to correct my open loop problem at highway cruising speed (bad mileage) and I tweaked the last few columns from about 2500rpm and up on the timing and fuel maps. The only spot I noticed any detonation was when I was already rolling about about 40-50mph and punched it. As the load and boost came up I got a little ping for a second. It's on the map in a mid load area at about 2000-2500 rpm I think which I didn't mess with yet.

Getting close. Here's a screenshot of the wideband reading and the ECUTalk log.

[Jeff Taylor]

Darinz - What system are you running to interface to the stock ECU? Bikirom?

To do this I think I'll need bigger injectors as the tuner thinks he'll need a lot more fuel to control detonation.

While needing the correct amount of fuel is essential, make sure your tuner does not forget about ignition timing. I am a big proponent of what Klaus Allmendinger has to say in his article (http://innovatemotorsports.com/resources/rich.php).

There tend to be two primary schools of thought for tuning a forced induction engine:

A.) Set air/fuel ratios """safe""" to a rich region around 10.5 - 11.0 on 93 octane and run relatively higher ignition timing.

B.) Set air/fuel ratios to the region where gasoline produces the most power between 12.5:1 - 13.5:1 (less than 1% difference in max power in this region, so I choose the richer AFR of 12.5), and retard ignition timing slightly.

Per Klaus' article, I tend to go with option B. As it makes most efficient use of the fuel, and retards the flame front by retarding the ignition timing, as opposed to retarding it by an overly rich air/fuel ratio.

What I'm getting at is: You do not necessarilly need excessively rich air/fuel ratios to control detonation (11.5 or richer). You will be able to still control detonation very well with a reasonable air/fuel ratio (12.0 - 12.5) and retarding the ignition timing.

You may already know this stuff, but I figured I'd take the opportunity to post about it anyway.

[Hodo]

You know after I yanked my stock 95 injectors out of my engine... I looked at the numbers. And they are the SAME injectors in the Z32. So I was going to just direct swap the Nismo 555 into my engine but I am staying all motor.

[qsiguy]

Good info Jeff, thanks. Basically what I was shooting for anyway but it's nice to see it in writing.

[darinz]

I'm using a complete aftermarket ecu. It is an Autronic SMC and there CDI system. The SMC is pretty basic as far as auxillary controls go but it is a very very good ECU. ie the only thing better would be a full Motec system. Rather than going for one with all the bells and wistles I got a CDI to ensure really good spark and also as it simplify's ignition wiring by removing the need for the ignitors. Also no O2 so leaded avgas or racegas is possible.

I hear what you are saying about afr's / timing and detonation and we are working to those principles. I'm not a tuner by any stretch of the imagination. I know what I want and have a good tuner who does it for me. As I understand it he has set the afrs to the max power region and then adjusts timing to suit. He always goes on about the amount of fuel he takes out of cars. Their speacilty is tuning XR6 turbo Ford Falcons and fitting superchargers to XR8 Falcons. (which the Oz and Kiwi guys will understand)

Sometime next year we plan to drop the compression and tune it for 98 ulp pump gas. I need to for some comps as we spend a lot of time travelling in between stages so need the ease of refueling.I have run it on 95 (as that is the best I can get at home) and an octane booster that in theory took it to 100 octane. With that it would detonate under medium load so not good but it got me home!