JohnBlazeLTZ

Have any of you guys with Centrifugal blowers had success blowing thru a TBI? It can be stock or modified...I just want to hear about some of your experiences. I have a TBI blower and I want to know if it would be successful to blow thru a TBI. Most people I have talked to on other websites say TBI is bad and they solve all the issue with a carb. Of course that is the easy way but what if I want to take the road less traveled and use TBI?

This is what my kit looks like:

fast82z

iTrader: (1)

I don't see there being a problem, just have to up the fuel pressure with boost just like any other blow through setup.

JohnBlazeLTZ

That's what I thought...some guy on another board was talking smack and I was like..."dude...don't make me bring the ruckus of the whole "TBI nation" in here to put the smack down on you and your nonsense..."

Actually...with the FI...I have a sandwhich adapter plate that can be fitted with two additional injectors that operate on an old Haltech computer. It acts like an on/off switch...it has a vacuum line that causes it to turn on under boost and tune off after boost has diminished.



From talking with BRob a LONG LONG time ago...I think he said that the EBL can run the 2 secondary injectors at the same time it runs the two up top.

This is the way I see it...tell me if this is wrong but...that way I could run a BBC 850CFM TBI with ?? lb/hr injectors up top and then two additional supplementary inejctors indearneath it for the extra fuel for the blower.

Can anybody estimate how much boost would be required for a 383?

JB

Ronny

iTrader: (1)

You understand you will need a 2 bar MAP sensor? Aftermarket or I think the Cyclone/Typhoon GM unit is used.

fast82z

iTrader: (1)

What do you mean by boost required by a 383? I'm guessing fuel needed, and that will be determined by your power goal.

JohnBlazeLTZ

Yes but I didn't know the Cyclone/Typhoon one would work. Thanks for the heads up. I was going to use the Flash EBL to tune. That has a 2-3 Bar MAP plus I thought it would be the best to use.

JohnBlazeLTZ

Well...here's the thing...the A-Trim blower I have is only 8lbs of PSI max. I just thought at some point...8lbs. wouldn't be enough PSI for a 383. Am I wrong in this? Set me straight if not because I am not sure really. I notice you were pushing 15lbs...but you were dragging right? Most people have told me AT LEAST an S-Trim...one guy told me a T-Trim but I figure for a T Trim...that would require a 1000CFM 4 barrel TB anyway and that would mean MPFI probably.

There's not a lot of people outside of 3rd gen (that I have found in the everyday world) that take TBI seriously and I am not sure why. Most people look at it as medieval technology. They don't believe guys like Fast can make it "go" like he does.

BTW...honestly as far as goals go...I was impressed with TBI Max's 383...and his estimates on his enegine were right around 360hp or so...that falls inline with a lot of 383 TBI's "advertised". I have seen Vortec headed 383 "advertised" between 360-390hp. That by itself is great...but I figure a blower could up that a little bit. Also...I am not "too" concerned by HP so much as I am mostly after TQ. If I could get into the upper 400ft/lbs of TQ range...that would really get this whale body Caprice moving...that's my true goal...to get it really moving but not be a drag car because I want it to be street driven. A car that big just get up and go with out some TQ.

I understand that the internals would need to be pretty stout and that means forged parts but I am not sure with those goal numbers... I need all Forged. Some guys have said they have 5-600hp on a stock type crank.

Bottom line is this 430hp/490ft/lbs. I think I would be dreaming for 400 at the wheels but...hey...what ever happens happens.

alexisgreene

To calculate estimated power:

bhp/cid * cid * (boost + atmospheric pressure)

bhp/cid depends solely on how efficient your engine is running in ALL areas. "Normal" values are 0.052 at the low end and 0.077 at the high end.

So to get an estimated power output of your engine:
0.052 * 383 * (8 + 14.7) = 452.0932 hp at the low end
0.077 * 383 * (8 + 14.7) = 669.4457 hp at the high end

Substitute 14.7 for the actual atmospheric pressure where you live, and determine bhp/cid for your engine and you will get a more accurate estimate.

Do you believe your rotating assembly can withstand this power output?

Assuming you will want a 6k redline and 90% VE...
(383 * 6000 * 0.5 * 0.9) / 1728 = 598.4375 cfm

Add boost...
1.544 * 98.4375 = 923.9875 cfm

The 1.544 is your pressure ratio at 8 psi by the way. So at 8 psi you will flow 924 cfm of air to your 383. Or 64.75 lb/min.

You can use this to determine how much fuel you will consume. Assuming you run stoic (14.7:1 A/F) and have a BSFC of ~0.5, you will need a fuel flow of about 264.29 lb/hr.

As long as the throttle body can meet the ait flow requirements and the injectors can meet the fuel flow requirements, there should be nothing stopping you from blowing through the TBI. As long as the injectors can overcome the pressure that it.

I apologize in advance if I made a mistake with these numbers.

EDIT: You are looking at near 528.58 hp based on the fuel flow calculator I used.

JohnBlazeLTZ

Alex...man...how did you know all those calculations? Wow...man...I don't know what to say but that end number is WAY higher then I would've ever thought. I know some FULLY forged Rotating Assembly CAN withstand 1000-1200hp...and I also know that some cast cranks...like the Scat Cast 9000 Series have been routinely dyno'd at 600+hp even thought they say 500hp would be the top of the line for safety reasons.

Would I build that powerful of an engine? Uh HELL YEAH! Should I with gas prices the way they are...UG? Honestly...I would be fine with a car that has less power and be more street-able. My friend had a nasty blown Mustang for a while but it had a "drag strip assortment" of parts on it and was difficult to drive around town. He ended up decreasing the Cam, Intake and TB. The car although less powerful is much more tame now. I think its a better combination of parts over all because the other combo was TOO radical. Out of all honesty, it was flat out scary to drive around town. It built very little boost down low and you had to really give her to get it up and moving. The it would top out SO far into the RPM range... I don't want that scenario. I have no intention of seeing much strip time and neither did he...that's why he changed it around.

Some guys have emailed me with parts ideas...you guys should throw around those ideas in here so guys can talk about them.

Ronny

iTrader: (1)

My understamding is compression is a factor as well on boost level. Seems you need to chose moderate compression level in bild. Late model engines seem to have less issues with boost even though they have higher compression.

JohnBlazeLTZ

Absolutely. At one time I was planning for a 355ci and was going to go with 9:2 to 1 compression. Now that its a 383...what would be ideal? Who should I consult/what should I consider? I am not sure with the larger engine. 383 already have lower compression I think. I have seen rotating assemblies with -12cc--18cc dished pistons. Its my undertstanding that a dished piston is the way to go with a blower. I am not sure what head/piston combination would be best for the PSI range on the blower.

JohnBlazeLTZ

Also...can anyone shed any light on the diffeence in rod length as far as 5.7 vs. 6.0 go? I knoe the 5.7 is the 350 rod right?

Ronny

iTrader: (1)

Eagle forged crank shows 350 cid with 5.7 inch or 6.0 inch rod lenght just a diff stroke(3.48 vs 3.75).

Eagle cast shows 5.7 rod lenght inch for both 350-383 but longer stroke for 383(3.75).

JohnBlazeLTZ

What advanatages/disadvantage do either have? I think I have read that it comes down to outward pressure on the cylinder walls...and minimizing the wear to the piston rings. The 383 is a great engine but is supposed to have some draw backs if not built accordingly. I THOUGHT the shorter Rod was preffered but I have recently read that places like PowerHouse or Smeadings won't build a 383 except with a 6.0 rod. I am not sure which would be better under what application...that is either Blown or Naturally Aspirated.

Ronny

iTrader: (1)

I dont have a clue? Sure appears the rod has to be matched to stroke(crank) and piston height. I see lots of differing combos. Deck height has to a constant to a degree.

Fast355

iTrader: (2)

Blow-Through TBI has been done and it can work. You will need some good fuel pressure and some large injectors as well as the EBL and a 2-bar MAP sensor. I would honestly go with the EBL, Accel 4bbl TBI, and 4 Peak & Hold MPFI injectors.

http://home.alltel.net/mcfly/tuning_fuel.htm

va454ss

iTrader: (1)

Only issue I've seen with supercharging TBI is leakage at the TB shaft. I know Vortech has you drill the bottom of the TB so it is pressurized.

The shaft can also be oringed or have sealed bearings installed.

fast82z

iTrader: (1)

With the piston/head combo, I'd say either -12cc pistons with 68cc chambers or -18cc pistons with 64cc chambers both being around 9.5-9.6:1. If you plan on iron heads I'd aim for 9.0:1. Both of these could go up depending on how big of a cam you're using. Last year my motor was 10:1 compression with 10psi and worked completely fine on 91 octane, but the cam was 246/254 duration @ .050. You could do lower compression though to leave room for higher boost; might give up some low end, but in boost it won't really make a difference.

With the connecting rod, I've heard that some prefer a 5.7" rod because it leaves more room for the rings. I've always used 6" rods though, and see no problem with it. Cranks will accept rods from their rated rod length and longer. The pistons then need to be made for that stroke and rod length to get the correct deck height.

JohnBlazeLTZ

Thanks for the link Fast that was good stuff.

Which Accel 4bbl were you thinking of? What are peak and Hold Injectors?
----------
OK...Thanks man...that answers my questions really well. I am just concerned about the engine living for a long time. If it were to be built then what would be the combo that will last longest by being built right.

How did you decide what would be good for you and your needs?

liquidh8

Johny, I have the same injector plate w/computer for the turbo project on my ebl TBI 350 chevy. If you go to VORTEC's website, or google it, it'll show you how to mod the TB with bleed hole to keep fuel from getting pushed out of the throttle shafts. Look for the 88-9something TBI SC kit and D/L the instructions. There are a few guys over at the silverado SS forums who have the SC kits on their BBC. I figure if you get the BBC TB and injectors, a boost referanced FPR, and use that plate, you should be good. EBL would be better since you can use it to dial back timing and increase the PW of the injectors on the TB. Use the aux injectors and computer also. With the EBL you would need the 2 bar MAP to take advantage of the boost controls.

I ended up getting a buick GN equiped buick station wagon, so I may not do the twin turbo TBI V8 in my chevy wagon.

Anybody know what size those 2 injectors are? low z or high z??

Keep us informed on your progress.

JohnBlazeLTZ

liquidh8..

Hey man..thanks for the reply. I really think I will only use the TBI equipment to start out with. I really think a BB 2 barrel TBI should work for the time being. Even if it were limit HP...that would be fine. I would rather spend the extra money on the long block...so it can withstand more later. I figure starting out with the BB TB and a good intake would be pretty important. Good fuel is an obvious one of course but if the air isn't flowing into the engine good...it'll be disappointing from the beginning.

The Flash EBL in my opinion is the ONLY way to go...I would be seriously interested in doing the MAF upgrade to it that Fast did too...

liquidh8

I concur, EBL and BBC TB would be the way to. The BBC is 670 CFM, You could get a bigger 52/54 mm TB and I would think fuel control would be the issue, not so much airflow. Till you get to higher HP levels. But you could make some good HP on low boost with the TBI system, as long as the control is there. i.e., the EBL. Good luck and keep us informed.

JohnBlazeLTZ

Which TB should I be looking at guys?

This 50mm 750cfm one?

http://cgi.ebay.com/ebaymotors/454-3...mZ370063783633

or this 54mm 850cfm one?

http://cgi.ebay.com/ebaymotors/454-3...mZ370063784013

or should I go with stock/un-modified?

I thought that the 54mm 850cfm one would be better because its bigger. Am I wrong in thinking this way? Would the 52mm 750cfm one suffice? I probably will not be putting a lot of boost through this...I am thinking of about only 8lbs. I figure with the 2 barrel TB...I'll keep the boost low. Then later on I can upgrade the FI system for more boost if I want. I just want to keep it street-able.

BTW...has any body seen this?

http://store.summitracing.com/partde...5&autoview=sku

Any thoughts on this?

BTW...I suppose this would be the shiznit huh?

http://cgi.ebay.com/ebaymotors/ACCEL...mZ330269722753

what intake would I use and how would I match fuel rails?

JB

liquidh8

I guess it depends on the power you are looking for in the end. With a lower power, low boosted app, you can get away with a smaller TB. But if you don't have anything, I would get the biiger one from go.

I saw the motorvation unit, accel used to make those. I had thought about going that route also, and using the ebl to control it. You can get just the TB with the rails and injectors. Keep an eye on fleebay to, i saw a few on there.

But, if you are trying to go on the cheap, and already have the vortec kit parts, i would get the ebl, a better FP, and regulator, and use the TB you got.

Vortec made those kits for small and big block chevys, utilizing stock injectors. If I remember right, the supplied regulator is boost referanced and the stock one is bypassed anyway.

83 Crossfire TA

iTrader: (2)

yep, you made at least one obvious mistake, but it was probably a typo... "Add boost...
1.544 * 98.4375 = 923.9875 cfm"

should have been:
Add boost...
1.544 * 598.4375 = 923.9875 cfm

the rest of the numbers are close enough to give the right idea so I didn't try to compare what you got with rules of thumb and conversion factors since you'll always get a little bit of a different answer.

Anyway, point being what I've said before, the airflow is there, you should be able to get 600cfm through a TBI TB and intake, heads can be swapped if you don't have the flow there (you'll need about 215cfm flow on the intake ports a little below your peak lift), all you need to figure out is how to get enough fuel into the engine (my first choice would be a spacer under the TB with a couple of _large_ injectors mounted in it, a pair of 160pph ford injectors added to the stock ones should feed up to close to 800hp)

Again (I've laid this out in detail before in other threads), the advantage to the whole thing is that TBI is easy to adapt to the rest of what you need and would also inject the fuel further upstream leading to better mpg in normal cruising and an intercooling effect under boost...

alexisgreene

I'm surprised nobody caught that when I posted it lol.

gmc350power

Hey bud name is andy. Just bought a turbo on kit and boosting my gmc tbi as well. I was just wondering where you got the extra injector plate. I can't seem to find out what the name for the part is. Could you please help. Thabsk

JohnBlazeLTZ

Hey man.. this is an old design from Vortech that is no longer made. I imagine it could be custom made though... the injectors were Ford SVO style. I sold this kit many years ago. My advice would be to just get rid of TBI and go with a 4 barrel TBI with self contained injectors like these... this one is designed to blow through out of the box and its pretty cheap... heard some good things about this company.

http://fitechefi.com/default.asp.pg-GoEFIPowerAdder

Take care.

JB

Travis Miller

itll work just fine iv turbo'd a few tbi they dont mind at all it actually works really well

Ronny

iTrader: (1)

WOW this is an old thread…. If we are using a 7.4L TB and then equip it with 75LB inj's and run max FP still it may (will) have have insufficient fuel. AKA LEAN. You will need a fuel pump that provides a lot of same. FPR will need to be way way over 20 LBS. I ran a Aeromotive that offers low pressure or over 20 lbs FP. I was at 21 lbs with stiffer of 2 springs provided. I think my motor was at 350 HP NA. Adding a small blower the fueling is insufficient. Not sure how one can overcome that issue
Port fuel is the answer.
I ran TBI for quite a few years. Now a 396 SB port fuel(nitrous) and may have insufficient fuel today. 150 miles on new motor....

Bubbajones_ya

I\m not trying to argue by any means and imagine you have significantly more experience with this type of setup than I do, but it appears that a 454 TB with 80lb inj's on a 350 fuels my setup well and could potentially support even more with the limited experience I have with it.

I just got my turbo setup running relatively decently not too long ago but my AEM wideband reads around 10 af/r at wide open throttle when I'm at 7psi of boost. My fuel pressure regulator (aeromotive 13301) is boost/vacuum referenced, and set at 20psi (with no vacuum lines hooked up) but sits around 12 at idle with vacuum. I don't' remember the fuel pump model number I put in but it's one that's frequently referenced here that's a drop in pump normally in later vortec style trucks.

I'm not good at tuning at all (I have the EBL setup) and my car really needs to be tuned badly, but it seems to be able to be made to run rich even at 7psi of boost.