lallend

Hello all,

Here's the deal. I've ordered a SB 427 crate motor for my 87 coupe... Link

I will be using...

Accel/DFI Gen7 and a dual sync distributor to fire injectors sequentially
TPIS Miniram intake
EM 1 3/4" coated full length headers, no cats, Corsa exhaust.
Car now has a D44 w/3.45 gears, a 700-R4 from Pro-Built w/3,200 stall Vigilante converter and fully Heim-jointed rear suspension.

What I need advice on...

1. Throttle body size and recommended manufacturers part numbers
2. Fuel Injector size and recommended manufacturers part numbers
3. Recommended fuel system upgrades (fuel pump, fuel line sizes, etc, etc) with the possibility of adding a 100-200 shot of Nitrous later.

Naturally I will contact TPIS and World Products for their input, but you guy's have been there, done that

Intended use of this car is simply, to be a nice street car.

Any and all conversation about this matter would be greatly appreciated

vader86

http://diabolicalperformance.com/Dia...alvette90.html

plenty to read there

Blown Vette

I would consider the XFI or Big Stuff 3. Very few of the major players use DFI anymore. The guy I started with close to twenty years ago don't even sell them anymore.

Gamewood

1. holley's seem to have better quality than other so my first choice would be their 58MM with nitrous (you will want nitrous in a few years...trust me) Otherwise Arizona marine sells a mono-plane. The holley will net you more a little more control at idle to low cruise...the monoplane will of course get you an extra 2-8 hp at high rpm.

2. Some like them truly big, most have decided that moderation is the key. The driver for injector size isn't displacfement but your heads and cam. You'll want to provide for 12.3 to 1 at 6000 (your max rpm). Your heads will determine how much air is going in the motor. FMS 30 lbs would be my starting point, with 36's not being out of the question. Smaller injectors will allow you tune idle more easily, but you lose the sure-ity of getting 12.5 AFR at RPM.

3. Install the motor with the current system. You will want to upgrade, but you'll have enough gremlin as it is. Get the motor in and broken in. Most of the pump kits i've seen just go in place of the stock unit.

other notes: You mention a TPiS miniram...consider going with a EFI'd single plane instead. You'll end up with more torque. The MR runners are so short that they never really give you a dynamic charge of air...they just flow really good. The various single plane out there will actually help the higher rpm's with a dynamic-tuned pressure wave to the heads. Talk to world about it as TPiS will try to sell you a MR at ~$1300. Or you could go for the ultra torque of the SR or "first's" TPI setup. I believe the First setup has larger runners than TPiS.

For the money your spending on the crate, you're gonna find 383 guys with similiar numbers. Think of ways now to increase your hp:displacement in the more sexy 1.2 ro 1.4 range. A good set of heads. Seems like the motown will port well, too. These crate motor never seem to push the CR envelope, but if your going to go nitrous keep it low (ie don't mill your heads down for more CR). Definitely consider coating for the cambers and valves. Finally, look at getting a solid roller comp cam setup. Your displacement will allow you to run a much larger cam before the idle starts to deteriorate. consider the lowest solid at 236/236, but you're gonna find a lot of the big displacement dude going with much bigger.

Gamewood

Also call Force EFI as they will be able to give you answers on EFI and intake options.

tjwong

Good luck finding a DFI system from Accel there are none to be had from them at this time. Unless you find one at a stocking dealer that has one on the shelf, Accel can't even give a date on when they are expected to arrive.

The engine you are planning on purchasing doesn't have a roller cam per their build sheet. That surprised me, also if I were you I would be looking at a manifold something other than a Mini-ram. Having a shoe box with short runners and a hot solid lifter cam is going to be full of reversion in the intake tract making tuning an issue as well as drivability. I would be looking at a single plane conversion such as what Jeb has been doing. The engine will breath better and make more power. Depending on the cam you eventually choose either a FAST or BS3 EFI would work well. You can even make the stock system work if you have the time or find a competent tuner with a load bearing chassis dyno to tune the beast.

For injectors 36 or 42lb injectors should be more than adequate. A Walbro GSM340 fuel pump in the tank would work well. If you are planning NOS then I would upgrade the pump to a large in tank Bosch unit that is the same as what Accel sells as part of their DFI kits. That pump supports 700+ hp. I think the short number for the Bosch pump is what is referred to as the GP-214 pump. There is no real need to upsized the fuel line size.

jerkyboy

with all of the above. I would use a converted single plane intake. I am running a stock miniram on my 434 and I can't seem to tune out the reversion at low rpms. I am sure I am leaving some hp and definitely torque on the table with the miniram. Also, my mini seems to have the distribution problems others have seen. my # 7 and 8 sparkplugs are always leaner than the fronts. I am running the walbro in tank pump with stock lines and never have run out of fuel. I have 42# Ford injectors and at 6500 rpm I was sitting right around 85% duty cycle with AFR around 12.5. I would probably drop down to 36# if I did it over again. It also seems as though the newer engine mgmt systems are the way to go i.e. Big Stuff etc...Good luck and let us know how it turns out

lallend

Thanks for the link, his Crankcase Evacuation System is facinating!

lallend

Interesting, Makes me wonder why the lack of interest in the DFI unit. Price? Performance? Reliability?

lallend

Very good info! Much food for thought...

When you say "Install the motor with the current system", are you suggesting that I get it up and running with the TPI system first?

lallend

I already have a DFI system from Accel (p/n 77022) so guess I will be starting out with that and learning as I go.

I have heard of the reversion issues w/the miniram but thought it could be tuned out... apparently it ain't easy? I mainly considered the Mini over SR because of it higher RPM attributes and ease of maintenance/installation etc. That plus to be honest, I haven't read much about the custom single plane designs as they are relatively new compared to the miniram which has been around a long time. Oh yeah, I am trying to avoid getting a raised hood for clearance as well.

Thanks for the fuel pump info... specially by letting me know that the stock sized fuel line size

lallend

Very valuable info!! Thanks!!

Which Walbro unit in particular are you using?

Thanks to you and the others I figure this so far...

Same pump as what you are using
Holley 58mm TBody
36lb injectors
Stick with the miniram or not...

jerkyboy

I can't remember exactly which pump I have. I wanna say Walbro 340M?? I believe it is 255LPH. It's monday and my brain has not caught up

AKS Racing

I ran the MRII for about 5 years. I was always fighting the 1/2 rich cylinders, 7/8 lean cylinder issues. I think this becomes more of an issue as the HP increases. I wound up replacing the MRII with a C4SP. It will clear the factory hood, as seen on my '87.

One bit of advice, if you go this route, get a good/qualified shop to weld the bungs to ensure they are all at the same height and angle. It will save a lot of aggravation in the long run.



Aaron

yedister

For my 434 with 15 degree heads, we started off with a stock Miniram and cut it to ribbons then welded and epoxied it to death till we got equal flow thru all the cylinders so I don't think we will have those 7/8 problems. But we won't know till it makes big noise on the dyno. As for the short runners, that is true it is short and your going to loose a bit of low range torque but the mid and high should bring it back. The EFI tuning will help. Reversion is a problem with the tuned length of a manifold column and what it does to a carb when you see the fuel hovering over the top of the carb. Take the tall air cleaner off a bug and you will see it at around 3000. If you put a low air cleaner on it, it will hit the top and run rich as a pig you can see the fuel wash on the underside of the cleaners. Yet that has a looooong runner, It is all about rod lengths and stroke and column sizing along with cam timing thrown in to boot. For those that have a dyno software, wash it thru the computer program and see what it does. The Miniram became really turblent around 305 cfm. For those of you that heads that flow more than 300 cfm with a Miniram, do you reversion problems or #7 & #8 cylinder problems? For those with less than do you have the same problems? This would be useful in determining the limitation of a Miniram. Does any of the forced induction guys with Miniram have the same problems?

yedi

AKS Racing

The example mentioned above was with heads that flowed just under 320 CFM, and was also in a FI application. Additionally, I spent lots of time, cutting, welding, and flow bench testing on mine. I really evened up the flow numbers (there was lots of casting shift in my MRII) with the work.

I still was not satisfied with the lean/rich situation on the MRII set-up. It was so bad that I refused to run on the dyno much over 6K RPM, even though HP was still climbing. I am getting nice "even" plugs with the C4SP.
Aaron

Bruce Witherspoon

I race an L98 with the FAST fuel injection an also tune for the people that acquire it. I know people who have used the Accel and Holley injection who contnue to return to the FAST because of it's simplicity.

Bruce Witherspoon

Reversion is a problem with any longer duration camshafts. I tried to run my stocker in speed density mode and had to go back to alpha N because of the reversion. Seems the MAP sensor does care which way the air is going.

lallend

When ya figure it out, let me know

lallend

Hmm, not trying to be an innovator here, just what is tried and true.. Damn...