MaNiAk86

iTrader: (2)

i am planning on dropping a built 383 into my car and i wanted to use the tpi setup so it would look stock. If I convert to speed density than i can make an intake easier without dealing with the MAF. Is there any advantage to speed density or should i stick with my MAF. I am expecting about 450 hp at the crank.

Also i want to spray a 100-150 shot.

brutalform

If you put a "stock" TPI intake on your 383, you will not make 450 at the crank IMO. You should really consider a S/R, or a M/R, or a HSR for your 383. A stock TPI is a restriction on a stock 350, let alone a 383. If you stick to MAF, the engine will generally accept your mods better than a S/D. Tuning should be done for either application,IMO, but, it is a must for the S/D. You can do a search on the pros and cons of each system, then you can decide for yourself what route you would like to take.

superGMman

I'd reccomend getting the speed density becuase if your going to spend money on a good 383, I would make sure I would leave myself room for the intake, which you will need.

MaNiAk86

iTrader: (2)

im not using a stock intake manifold. i was planning on buying the edelbrock lower intake for vortec heads and hi flo runners and porting my stock upper intake.


also what size injectors should i use?

Floor guy

Mass air works well for a dummy like me. Stock programming has been in my car since 1987. I am satisfied with how well it has adapted to the changes I have made. This applies to drivability and 1/4 mile et. Could custom tuning make it better? Possibly. I am not interested in paying someone hundreds of dollars for the "perfect" tune? No. Am I willing to spend months learning how to tune? No. I am not also in the mood to buy the equiptment needed. Long story short, Try the mass air and see how it works for you. I have always thought that the map vs maf debate was silly. For me, mass air is the only possibility.

MaNiAk86

iTrader: (2)

thanx for the input. the only reason i wanted to covert to speed density is because i just wanted to slap a K&N open element on it. but ithought of this cool ram air setup using a corvette air bridge to put the airfilter down into the air dam.

Floor guy

Don't get me wrong. I am now trying to discourage anything. Speed density requires a commitment. Mass air is more forgiving.
For me, the choice is clear. Most seem to disagree with my thinking.

doc

With the fuel needs of a biult 383 and 100-150 shot of N2O, I would install 30#/hr FMS injectors.

For drivibilty, the de-screened MAF should be your choice, I see nother wrong with it. However, you will need to get a custom chip because 1) 383, and 2) 30#/hr injectors, not to mention other reasons.

But a MAP car can also be tuned very well and then you remove any doubt of air restriction caused by the MAF.

FWIW: I'm still running a de-screened MAF setup on my 395 stroker. But I program my own Eprom chips.

fisherbody86

The speed density setup uses predetermined tables for an assumed air volume flowing through a stock motor. It is calibrated to work with the stock settings and does not adapt to change. If you just drop a 383 that makes all kinds of power in a speed density car, it will not understand what is going on. It will see conflicting readings from the MAP, 02, and TPS. It will not run well at all unless you burn your own prom. To do that, you will need to know all sorts of information on air flow, volume, fuel and spark curves, etc. It is ALOT of work to make a speed density engine managment system power a built motor.

On the other hand, MAF actually measures the airflow and has the ability to adapt to change (to a certain degree). It can tell that your motor is breathing more and can make necessary adjustments. You will still need to tune it, and prom burning still might be necessary.

One more interseting note. Mounting a K&N filter right on the throttle body of a speed density car does look cool. But it causes a lot of turbulance in the plenumn chamber, and robs somewhere in the nature of 5-8 hp. Having the 8 or 10 inches of ducting infront of the throttle body helps to smooth out the air, letting your inherently long runner TPI setup breathe easier.

Go MAF, and dont mount the filter on the throttle body.

brutalform

With a speed density system, the one thing to remember is, the system does not know if you have a 305, or a 434. The cubic inches, injector constant, and modifications are invisible to a speed density system. If you have a 383, and you adapted a 305/350 S/D setup, the system still tries to manage the engine it is supposed to.

Grim Reaper

If you have a high revving and/or big inch SBC, you will still need to modify the eprom even if it is MAF. SD requires more "hands-on" tuning (and time) to setup everything right. But MAF must also be modified as mentioned by doc if your injector size changes OR if you max the MAF limiation of 255 gm/sec (which is easy to do on a high revving and/or big inch motor). The usual fix is to increase fueling via the P/E tables at the RPM levels above the point where the MAF maxed out.

Also, if you modify the MAF itself, you really should "re-scale" the MAF Scalar Tables (which can be a really bitch unless you have a Romulator or some other program to "tune-on-the-fly"....then it's a snap).

But if you have a perfectly good working MAF system, give it a try first before converting to SD. Personally, I would only contemplate converting to SD if you were having troubles finding a reasonably priced ECM at a wrecking yard and the MAF itself was burnt out. SD ECMs are a dime a dozen at wrecking yards as well as MAP sensors. But that would be my only reason for converting from a perfectly good working MAF system.

As for tuning, most engines respond well to a little extra spark, provided the engine is not experience any detonation (and causing the Knock Sensor to pull timing out).

MaNiAk86

iTrader: (2)

where can i have this prom burning done?? also what kind of fuel pump should i run?

Floor guy

The general view(as I see it) on the forum is :
The only way to do correct tuning is to do it yourself.
This is why I made my post regarding time and effort to do it.
It usually sparks huge debates over track vs dyno. Engine dyno vs rear wheel dyno. Mail order vs in person dyno tunes etc etc etc. It usually gets debated to death and winds up getting locked. We shall see.