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Topic: forced induction and speed density (Read 3814 times) previous topic - next topic

forced induction and speed density

ive been curious about this, i know how speed density works, i know how MAF works, but how well would speed density work with forced induction

fuel isnt as hard to control without MAF as you would think, there are so many things out there such as rising rate regulators, pinch valves, extra injectors, etc

an issue i was thinking, i know you need i think 15-17in/lbs of vacume, but to make power with forced induction, many times you need large throttle bodies, free flowing exhaust, and sometimes depending on the setup, a cam that isnt so hot for vacume, would that be possible to overcome?

im just talking out of my ass right now, im familiar with Dodges speed density system on the dodges, so i figured, why cant it be applied to ford?
It's Gumby's fault.

Re: forced induction and speed density

Reply #1
http://www.powerdyne.com/upgradekits.htm
The Speed density calibration kit listed on the above site is nothing more than a one way check valve that is designed to Keep your MAP sensor from reading boost.  Vortech sells one as well for about 25 bucks.  Its the only extra you need to supercharge a speed density setup as far as centrifugals go.  Upgrading throttle bodies and exhaust on speed density setups are not an issue.  The biggest issue on the cam is lobe separation angle.  112 degrees is ok, but usually will run rough.  114 degrees seems to be the best bet.  And as far as a Kenne Bell:
http://www.kennebell.net/pricelist/SC-PRICELIST.pdf
4th kit down on the 5.0 list is speed density specific.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Re: forced induction and speed density

Reply #2
do you have any specific cams that are known to be SD safe?

i did a little research and came up with some great info, but the thing that has me curious is injectors

if i were to do this, id definatly use a FMU or RRR (same thing, different name basically), but if i max out the 19# injectors, would i be able to say throw some 24# injectors in, and turn down the base pressure to keep it from running so rich?
It's Gumby's fault.

Re: forced induction and speed density

Reply #3
The Kenne Bell Kit for speed density comes with an fmu and bigger pump.  All the centrifugals come with FMU's some come with bigger pumps.  In 5 weeks I'll be putting a Powerdyne 6 PSI setup on the Demon.  1600 plus the price of the check valve and tax will keep me under 1800.  I SHOULD take about 8 tenths off a car that has run a 13.6.  As far as cams go for speed density STAY AWAY FROM THE FORD MOTORSPORT CAMS!  They are made specifically for mass air.  Back in the day when they were the only thing around for a computer controlled 5.0 it gave people no choice but to do the mass air conversion.  Nowadays there are a lot of SD came that are safe.  Heck the stock HO cam aint bad for a blower.  There are others as well.  Crower part #15511 is an excellent speed density cam with the HO firing order.  Crane makes some good ones as well.

Injectors: FPR and 24 pounders will work.  I've heard of people using 30 pounders on an HO computer.  Thats about the limit though.  I've used 19's on an SO computer with an adjustable regulator.  It passed NYS emissions and ran good.  I would love to see if an SO could handle 24's if it had enough cam and head.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Re: forced induction and speed density

Reply #4
awesome man, i appreciate the info, youve answered everything i needed to know

not often that happend ;)
It's Gumby's fault.


Re: forced induction and speed density

Reply #6
hmmm...more fuel...more boost...hmmm

also, im finding that quite a few guys over at turbomustangs.com run speed density, it appears that its easier to get a good baseline setup out of than MAF

off boost, itll drive just like it would bone stock, on boost is when you take the fuel into your own hands, most guys run FMU's and dont have many problems

theres a setup that stands out in my head for the power potential for cheap: stock block, E cam, mildly ported E7's, thicker headgasket and head shim for lower compression, equal length shorties flipped, 12psi on an intercooler, 440rwhp and 436rwtq, there are other minor odds and ends, but thats the general setup, im not aware of the turbo's that he used though
It's Gumby's fault.

Re: forced induction and speed density

Reply #7
Or you could use a speed density set-up that makes use of a MAP that can sense boost and will adjust fuel accordingly  ;) (<----future MegaSquirter...once I can get the time to get the friggen thing built :mad: )

Your Dodge turbo stuff was like that....
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon

Re: forced induction and speed density

Reply #8
I'd thought about that.  I'm unclear on what I would need though.  Iv'e heard the terms like two bar and three bar MAP used on dodge message boards, but never got any clarification as to which would work well/be easier to set up.  I'm just gonna hook up the check valve and FMU for my setup when it goes on next month and maybe if I get adventourous I will go the boost sensing MAP route.
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Re: forced induction and speed density

Reply #9
2bar and 3bar represent how much boost they read in simple terms

i cant remember exactly which reads up to what, other than 3bar goes up to 29psi, people get really technical when explaining it, so im not completely sure how it works

to make that MAP setup work, it would take a lot of EEC work, because youd have to take a computer that never see's boost, and make it see and comprehend boost
It's Gumby's fault.

Re: forced induction and speed density

Reply #10
1 bar = 14.7psi.

Atmosphere is 14.7psi...thus your std n/a MAP sensors are 1 bar.

2 bar = 25.4 psi absolute, or 14.7psi over atmospheric

3 bar= 44.1 psi absolute, or 25.4psi over atmospheric

IIRC the MAP sensor in my M-S kit is a 2.5 bar unit...or good to 22psi boost.
Long live the 4-eyes!  - '83 Tbird Turbo - '85 Marquis LTS - '86 LTD Wagon

Re: forced induction and speed density

Reply #11
Quote
it would take a lot of EEC work, because youd have to take a computer that never see's boost, and make it see and comprehend boost


Like I said.......Check valve + FMU for me :D
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Re: forced induction and speed density

Reply #12
hey Chuck, ive heard arguments that 2bar were 14.7psi, i forgot exactly what the argument was, but a few big guys at turbo dodges were saying that 1bar is really 0 vac and 0 psi, and 2bar was 14.7

any reason for them to think that?

Paul...thats the same route ill be going when i can make my project actually come together
It's Gumby's fault.

Re: forced induction and speed density

Reply #13
Quote from: Tbird232ci
ive heard arguments that 2bar were 14.7psi, i forgot exactly what the argument was, but a few big guys at turbo dodges were saying that 1bar is really 0 vac and 0 psi, and 2bar was 14.7

any reason for them to think that?

Chuck's post is agreeing with the turbo dodge guys.
 
psig= psi gauge
psia= psi absolute

Psia is the absolute pressure, period. In space, the psia is 0. At sea level, psia is ~14.7.
Psig is the pressure relative to atmospheric pressure. At sea level, psig is 0 and psia is 14.7. At Denver, psig is 0 and psia is 12.1.
 
Let us say you inflate your tire with a tire gauge in Denver to 35 psi (47.1 psia), then drive to the coast. Your tire pressure (which is psig) will now read 32.4 psi, even though the absolute pressure is still 47.1 psi.

Make sense now?

Re: forced induction and speed density

Reply #14
Pau, are you sure you can run a Powerdyne Superchager on a speed density set up?  I just got set up as a dealer for them, and asked about that specifically.  They told me flat out " You have to convert to MAF to run our stuff"  If you can run them with MAP, that would great to know, and pass on.  I have everything for a HO MAP conversion for my Cougar, but was putting the swap on hold to go with MAF, just so I could run a supercharger (figured it would make good advertising....lol, and easier to get the wife to buy off on getting one...lol)  Thanks for your help.