liquidh8

Nothing new on my hold up yet, still waiting on my brother. If I never sold him the engine I would be playing with it right now :drive:

I'm gonna head over to check out the thread about the center post hogged out. Was that unit ever flowed? Any issues with the fuel spraw running into one another?

va454ss

iTrader: (1)

I would guess you just set both normally for idle with the blades barely open to help shear the fuel. With a common plenum (open plane), whichever cylinder is on the intake cycle will draw as needed.

titchener

If it has to be sequential the plan is to have both blades start opening together off idle but have one set open much more slowly in the beginning and then catch up quickly at the end of the throttle stroke. This way fuel is not getting puddled up on the "slow" set of blades, that set is opening, just not as fast in the beginning of the throttle stroke.

It turns out the first simple linkage scheme I tried pretty much did this, so it would figure that it might turn out that rather than spending all the time perfecting a synchronized linkage I should have just stuck with the first "flawed" one.

If its true that the combo of different mixtures will both mix together and get sucked equally into a particular intake port rather than having the back mixture favor the back ports and front favor the front ports, then the sequential throttle blades could work even though the injectors all fire equal amounts of fuel.

I guess rather than reinventing the wheel on this issue I should try to find out how the Holley unit handles this problem.

Paul T.

titchener

I asked the question below on the ChevyTalk.com forum:

"I noticed (on a Holley C950) that like a 4 barrel carb the throttle blades open sequentially, which makes me curious about one thing. On these Holley 4 barrel TBIs, do the front and back barrels get fuel metered at different rates because of the different blade opening rates, or does the ECM always fire all 4 injectors at the same rate and duty cycle?"

and got back the two following answers:

"They only fire on the front until the back are slightly open, then swap to all four." (from Doug, the Holley guy and moderator)

"The ECU is actually capable of doing this both ways due to their older '1:1 throttle linkage' TBI units. However, even then, the rear secondary injectors are off at idle to ensure the pulse width isn't too low. The rear secondary injectors only spray fuel in accordance with the 'TBI Switch 2-4' value found on the 'Engine Parameters' screen and turn fuel back off in accordance with the 'TBI Switch 4-2' setting. Completely user programmable." (from Danny C.)

So it sounds like originally the units had synchronized throttles and then later went to progressive ones. In either case the only control available is to set the "secondary" injectors either totally on or totally off based on throttle position, and it sounds like this is used to make idle easier to tune.

This would be pretty easy to implement if it turns out to be needed, I'll just put a switch on the throttle linkage that opens the grounds on the secondary injectors when the throttle linkage is mostly closed. With a VAFRP it probably wouldn't be needed.

It also sounds like if you have to go to a progressive linkage for drivability, its ok to fire all the injectors at once as long as you don't dump too much fuel at idle.

Paul T.

rocko350

I've been refering to this as "Dominator Tbi". Hopefully this is ok. I would pay you to reproduce it at a later date as my engine is back out. Keep up he awesome work.

titchener

Rocko, Dominator TBI sounds good to me. I'm still moving ahead on it when I can steal time to work on it, pretty much last to do is a 14" air cleaner baseplate, I'm waiting for Moroso to ship me a bottom air cleaner plate and then I'll machine up the adapter for it.

I'm still interested in finding people willing to try one out, you just need to supply your own injector pods with injectors and have a EBL system to use with it, and if it works for you I'll sell it to you for just my parts costs. I'm hoping to give one a shot myself in the summer if time allows (my business, kids and nagging ex-wife gobble most my spare time).

Does anybody know what the fastest ET anyone has run using real GM TBI units is? It would seem this system might have a chance to break that record.

Paul T.

rocko350

ive already made 470 hp with a holley 950hp carb on the dyno with the 496. i'm gunning for the 11's in my caprice. It will probably take some chassis tuning time before i want to try for a hard top end charge. By the end of the summer i'll be on the chassis dyno again. I have to travel so much that i have zero time now that i have the money to do it. I have the parts to complete the unit, but i will need time to resort the combo. maybe 10.s NA is possible. enough air/fuel for 750hp?(need to recheck math).

Tbi-MAX

I was just getting ready to link him to you TBI, but you beat me..
I would really like to see this done with 2 BBC tbi units... as soon as you finish fab this up, let me know.

titchener

Rocko, the unit with its current stock bore TBI's should flow:
490 x 2 = 980cfm.

A common carb sizing formula for drag racing is:

Race Carb. CFM = ((Displacement * RPM) / 3456) * 1.1

So with your 496 spinning to 6200 RPM that works out to around 980cfm, so unless you plan more RPM than that the unit looks like it matchs pretty closely.

More RPM would require boring the TBI's oversize. Boring to 46mm gets you around 590cfm per unit for a total flow of 1180cfm, but I'm hoping to get the system working well with the stock TBI's first before trying it with bored ones.

As far as fuel goes, with stock 350 62# injectors, at the stock 12 lb pressure with 4 of them should be good for:

HP at 12 psi = (4 x 62)/.5 = 496 HP

To get to 750 HP:

New Pressure = 12 psi x (750/496)x(750/496) = 27.4 psi

So on a fuel basis even with stock 350 injectors the systems should be good for 750 HP if the fuel system is set up for 30 psi or so. On a air flow basis the formulas above imply that there should be enough flow for 750 HP, but that goes against the common wisdom that a single stock TBI unit is only good for 300HP, so its possible the units would need to be bored to make 750HP. I think the only way to find out is to try it, the MAP readings at full throttle will show if the units don't have enough total flow with the stock bores.

Even at a car weight of 4500 lbs or so (Caprice), over 700 HP should put the car in the 10's if its hooked up well, are we talking the world's quickest stock GM TBI powered car here?

Paul T.

rocko350

I've messed with fast street cars for some time now and wanted to build a full race car and use tbi on purpose and then step up to a homebrewed multiport system. Also ,this year I started racing in an east coast racing "series" called the ecirs. They graciously bent the rules to allow "any other cool b-body" in thier eligibility requirement. I was one of the first to run a tbi car against stroker 383 lt-1's. one guy is running a 421 supercharged stroker lt-1 with cylinder liners. A few are even running full tube chassis cars that go into the 8's on spray that are damn near full weight in "street trim". Its all in the name of fun. But fastest tbi title for a short time would be cool. definitely one of the first to the 11's in a caprice i hope with no power adder. Then again a 300 wet shot under the "dominator" would get me near 800hp......for a few seconds.......

http://www.youtube.com/watch?v=Jkwlm5iHAgs

Im not in this but the 502 engineering mule that john moss built is. inspiring to say the least.

titchener

"build a full race car and use tbi on purpose and then step up to a homebrewed multiport system."

You might be more competitive with a TBI system than you realize. 4 barrel manifolds have gotten pretty refined, and in full throttle applications like drag racing many find not much if any HP advantage in multiport EFI systems over a well tuned set of carbs, although the tuning is definitely easier. So a well sized and tuned TBI system could run right with a multiport system.

No matter which way you go thou it sounds like a lot of fun, good luck.

Paul T.

rocko350

No, the car was going to be stepped up then I changed my mind. I didn't relay that thought or intention too well. All of the other guys have multiport and i feel like beating them at their own game so to speak. Car is staying tbi PERIOD.

titchener

"Car is staying tbi PERIOD."

Alright, that's what I wanted to hear, a true believer.

RBob, if you're tuned in, what's the quickest 1/4 mile time you're aware of that someones run using a GM TBI based induction system?

Paul T.

rocko350

I caught the edit
----------
I caught the edit stock HAH!

F_N_JUNK

iTrader: (4)

Great job guys, keep up the good work........ but my question is why not just buy the Holley 4BBl unit???? I understand it's the fun and all of building one yourself and the challenge is a great time as well..... but Holley spent TONS of money developing theirs and it seems like you are looking for performance gains that a standard TBI is just not capable of IMHO.

RBob

iTrader: (1)

Yep, I drop by from time to time to check on the progress

How's 11.8 @ 119.1 MPH:

https://www.thirdgen.org/forums/tbi/...?highlight=ebl

Looks like Fast355 holds the current record with GM TBI stuff. Does make some power.


There was another guy that posted a number of years ago. IIRC he was running AMC's with GM TBI setups (duals usually). And again, IIRC, claimed 9 sec quarters? I'll see if I can find his thread.

{edit} OK, found the threads, he is using Holley parts (ECM & dual 4-bbl TBI units):

https://www.thirdgen.org/forums/tbi/...hlight=amc+tbi
https://www.thirdgen.org/forums/tbi/...?highlight=amx
{/edit}

RBob.

rocko350

i dont remember if the guy with the amx finished his car or not.

besides its not a third gen.

and hes running 2 4bbl holleyss with dual prochargers.

i guess i gotta go for 8's


Lets get the dual dominators going on a tunnel ram already.

TT 68

I just came across this post and have a solution for the linkage issue that is far simpler. I was thinking of doing the same thing last summer but never had the time to get past the planning phase.

An Astro van TBI unit has the throttle linkage on the passenger side pulling from the front. It could be turned around and used as the front TBI unit with it's fuel lines coming in from the front of the engine to work with a standard truck style rear feed driver side throttle linkage TBI unit. This way both throttle levers are pulling from the drivers side with no special effort.

If this could be made to fit on a standard Holley 4150 carb intake it would be far more useful to many more people.

I have a TBI housing with a broken air cleaner flange that I was going to try to weld back together. I will see if I can weld the stuff with my TIG welder this weekend. Some cast aluminums weld, some don't. Hopefully the TBI's are made from good aluminum and not pot metal.

Fast355

iTrader: (2)

Only one problem with that idea, the astro van TBI pulls from the driverside front. The fullsize vans, some S10s and some late model trucks also used the same setup.

titchener

So it sounds like these van TBI's aren't actually different, they are just turned around on the manifold?

That's ok though, the linkage I ended up with turned out pretty simple and it works well.

TT 68, definitely post back the results of trying to TIG weld on a TBI housing, I've been curious about if this was possible.

I'm still working on this project when I can steal time, I just need to finish the air cleaner adapter, I'll post pics of the finished unit in a month or so.

TT 68, I think it will work to make a 4150 flanged unit but at 980 cfm I think it will be too much air flow for engines that don't put out at least 600 HP or so, so it doesn't sound like it would be practical for most street engines, but if the dominator one works well I'll definitely fab up a 4150 unit if someone is interested in trying it out, I've got the adapter plate designed already.

Rbob and rocko, I missed your posts on the TBI ET's the first time around, sounds like if we're only counting cars with modified GM TBI's that this unit has a chance of grabbing the quickest GM/TBI ET title. I think it should be good for 650 HP or so, which in a 3rd Gen should go in the 10's if not potentially 9's.

F_N_JUNK asked "but my question is why not just buy the Holley 4BBl unit????"

F_N, for me the funnest part of hot rodding is going cheap for fast, especially if you can be beat somebody in the other lane that went the high dollar route. I think the TBI Dominator/EBL combo will potentially not only be cheaper but will possibly be a better system than the ones Holley offers.

Paul T.

TT 68

The Astro van TBI units fuel inlet is from the opposite direction of the throttle cable pull direction so it's throttle blades open in the opposite direction of the standard truck style TBI.

If the linkage is on the wrong side as stated earlier it is probably better since it would be cleaner and easier to make the linkage progressive by combining your fabricated lever with a shorter length and a slotted connection. I did this with the tunnel ram I had on my car a long time ago. The thing ran around on only the primary carburetor until you hit about 1/4 throttle and the travel in the slotted linkage bottomed out. The secondary carburetor linkage connection point was closer to the centerline and made it open faster than the primary carb. At full throttle they both were in completely.

This would work great with dual TBI's. You could run the engine as a normal TBI setup off the primary TBI and ECM with a piggy back ECM that ran only the secondary TBI unit with it's own TPS and what ever other sensors it needed to function properly. It could even have bigger injectors if you wanted it to but for tuning it is probably better that all four were the same size injectors.

The secondary TBI computer could even be a PCM to use as a trans controller if you wanted to put in a 4L80E.

TT 68

With a little adjustability to the secondary TBI linkage you could tecnically reduce the CFM rating by limiting the throttle blade opening % of the secondary TBI unit if you found that the 980 cfm was too much for your combination. This would also allow you to up the air flow if your combination changed.

Every 4500 series intake I have seen is too tall to work under my stock SS hood even without an air cleaner so that would also require that I buy a cowl hood to use it. Plus I all ready have a nice 4150 style intake and carburetor that are perfect for my combination.

I want to make the dual TBI conversion easy to reverse back to carb so I can do some back to back comparisons at the track so I really want to stick with the 4150 pattern intake if possible.

I considered building a main body to fit a 4150 carburetor baseplate that could take a pair of TBI fuel injector pods but the IAC and TPS issues make it a little harder to do than cutting two TBI units down to fit the 4150 intake pattern.

I can widen the carburetor mounting flange on the intake to give it enough material to allow the TBI throttle blades to clear or possibly mill the carb flange off entirely and weld on a new dual TBI mounting flange in its place. The remove & replace option would probably work the best for my limited hood clearance application.

rocko350

If the issue for other people using this unit is too much airflow, there are other alternatives, such as an extreme efi bored tbi unit. We are using this on 496 bbc, and a 540? (titchner), each spinning north of 6,000. ( launching from 4000 revs for me with a gutted 3800lbs with driver). But using the tbis in the standard forward mounting setup, on a carb mounting pattern, makes your fuel connections to the pod a little tight. The way its being done now, you can use all 4 lines to feed the tbis and regulate with a remote that is vacuum referenced. (sorry about the run on). hood height for this wasn't a concern, but a dominator flanged small block manifold is available. I had a Weiand one and can't remember what number it was. Anyways Brodix makes one now, that i believe is good for use on a late 60's, early 70's vette if I'm not mistaken, and edelbrock, still makes a single plane dual quad intake but that thing is mega expensive.

also on the issue of too much cfm, two 2.8 tbi units could be installed together on a 4150, i believe, because of thier smaller bores.

titchner, i should be pm'ing you in about a month for payment for one of these. I'm finishing the chassis so the engine can be reinstalled.

Dewey316

Offenhauser makes a low rise single plane dual-quad that isn't too badly expensive, and I think it is square-bore or spread-bore mounting, so it would work with common TBI adaptors.

If you look for the offy unit, I think their marketing name is like "360*" intakes or something, and they make a dual-quad version.

--John

Fast355

iTrader: (2)

The astro van TBI opens in the NORMAL direction, its NOT reverse. THe cable pulls from the front, but it is connected to the BOTTEM of the TBI unit. The linkage is on the side opposite the TPS.



Notice how the cruise control still pulls from the top, which means the TBI opens in the normal direction.

titchener

Sounds good rocko, I'm eager to have somebody try it out, it will be a while before my engine and car is ready. Since this unit is experimental I'll only charge you my material costs for it.

Also that's good input on using the smaller 2.8 TBI units for a 4150 unit, I didn't realize they made those, I'll have to check in to that.

Paul T.

jwscab

If you guys are worried about tip-in throttle problems with too large a cross section, you could always use a non-linear cable pull, like the monoblade throttle bodies. it's like a snail shell, or scroll type eccentric cable guide. when the throttle is pressed, the blades are opened progressively based on the throttle position.

I remember seeing a company that actually makes a bolt on bracket for throttles. I think it had more to do with the trans TV valve, but I can't remember.

OK, so it's called a variable ratio throttle linkage. oddly enough, here is what looks like a miata based site with a product:
http://biggulp.home.att.net/vrtl.htm

TT 68

While looking through the parts catalog for a rebuild kit for my wife's Demon carburetor I noticed that the butterfly's are the same size as a small block TBI unit at 1-11/16". The 750 cfm wet flow rating for the carburetor can probably be used equally for the wet flow rating of the TBI unit. It may flow a little higher than the carburetor due to the restriction of the boosters being a little more than the injector pod but probably not a whole lot.

The dry flow measurements may be much higher but I think based on the 750 cfm carburetor butterfly sizes that the wet flow rating of the small block TBI unit is only 375 cfm. This means dual small block TBI units would wet flow about 750 cfm which is very manageable for a 350 or bigger engine.

I laid out the Holley carb pattern in AutoCAD and added the TBI pattern over it. If the last bolt hole in the injector pod is cut in half on each throttle body so they share the hole then the dual TBI units should fit into a standard 4150 series carb base plate pattern. This is as tight as I think you can cut these down for use in a paired setup. This will need just minor clearancing of the intake to clear the way for the butterfly's to have a straight shot into the top of the intake to avoid puddling.

I have roughed out an adapter plate in plexiglas and it looks to fit pretty well. I think a bell crank type throttle linkage mounted off the back side of the adapter plate could operate the passenger side throttle linkage of the front TBI unit and allow you to do some kind of progressive linkage and still keep the TPS and IAC functional on the secondary TBI unit.

For progressive control to be adjustable I think the TPS needs to stay on the secondary TBI unit. Mine will be controlled by a pair of ECM's with the primary ECM running the engine like a standard single TBI car. The secondary ECM will control only the fuel mixture of the secondary TBI unit based solely on throttle position.

Now if I only had a milling machine I could get this thing worked out accurately in metal and start road testing the setup.

The tuning will be fun to figure out but I'm thinking running the primary TBI unit to 85% duty cycle and adding only the additional needed fuel with the secondary TBI unit. Adjusting the linkage to get the air in when needed for best power will be entertaining. Every movement of the secondary linkage will require new tuning of the secondary ECM.

I think locking the two together and basically turning it into a 750 double pumper carb would be easier to tune but much worse on throttle response. I may try this first as the carburetor the dual TBI setup will replace is a 750 double pumper.

In my case I need the fuel flow more than air since my vehicle will run on E85 fuel now instead of race gas and needs about 30% more fuel in the mixture compared to a gasoline burner. Dual 5.7 small block 55-pound injector pods at the 9.79 to 1 air to fuel mixture for E85 will only be about the equivalent of a single pair of 73-pound injectors. Not a tremendous flow gain but enough to run my 409 inch small block. Increases in fuel pressure over stock can bump that flow up a little if needed.

titchener

TT-

There's a guy who I think posts on here with the name "airdeano" that did a lot of nice flow testing on various TBI units, search for his posts to see the full data. On the stock 5.0/5.7 TBI units he saw 490 cfm at 1.5" hg, the same way 4 barrel carbs are tested.

That's why I think 2 of these units at 960 cfm will be too much for anything less than a killer-diller street engine that makes 600 HP or more.

However Rocko350's suggestion to look at the 2.8L units was a good one, they apparently are exactly the same as the 5.0/5.7 units except for a reduced 1.375" bore size. My quick "guestimate" on the flow on these units would be around 325 cfm or 650 cfm for the pair, a nice streetable size with plenty of room to grow with an overbore as needed.

I agree with you that by cutting the TBI bodies down more than I did for my Dominator version that they will fit in a 4150 flange size, it looks doable to me.

It will be interesting to find out if a progressive throttle linkage is required, I'm hoping for drag strip usage the answer is no, for the street I guess we'll find out. Jwscab's suggestion of a scroll type throttle linkage could be a solution also.

So bomb's away, lets get this to fly. If you're interested in trying a 4150 unit I can cut a baseplate for you after I get the Dominator version done.

Paul T.

titchener

Geez, I guess another way to go for a street setup would be a "Quadrajet" style dual TBI, use a 2.8L unit on the "primary" side with smaller injectors and a 5.0/5.7 unit on the "secondary" side with bigger injectors so that the injector size difference roughly matched the air flow difference. 62's (standard 350 injectors) on the secondary and 44's (305 injectors I think) on the primary would be pretty close.

490 + 325 would be 815 cfm, a nice size for an aggressive street build up.

God knows what kind of linkage would work best for this, but I think testing would sort that out.

Paul T.

TT 68

Any updates?

titchener

Some family and business issues have slowed me down some on this project, but I did seal the exposed passages in the cut down TBI bodies with an epoxy and that worked fine.

I tried to order a flat 4150 style Moroso air cleaner baseplate to use as a starting point for the aircleaner, but I guess they don't make the flat ones anymore, the one that came is curved and probably won't work, so next step is to figure out a different way to make the baseplate, if I can't find a flat baseplate I'll use the Dominator baseplate I already have for my carb setup, I was hoping not to have to cut that one up but oh well.

Paul T.

TT 68

I was looking at the air cleaner base plate issues as well.

I think it would be easiest to cut out the middle of a cheap air cleaner and only keep the filter lip and flat seal area of the original air cleaner base then make a new dual TBI shaped middle section that can be welded or riveted in place.

I thought about splitting the remaining original center section in half, positioning it where they align with the outboard points of the throttle bodies and then making a filler to joint the two halves. It would save a little fabrication time and could incorporate a smooth radius transition into the throttle bodies for a little better air flow than a flat base would give you.

titchener

I decided to get off my rear and finish all the machining on this project, the pics below show how it ended up.

You can see the air cleaner base adapter, all that's left to do is to machine the air cleaner base when it shows up to bolt on the adapter frame.

You can see the "holddown" clamp in the center, the allen head bolts you see on it go through the original air cleaner stud holes in the TBI units and screw into the base plate to clamp down the end of the TBI units that had the mounting bolt boss machined away. The holddown clamp also holds the new air cleaner stud.

Stock injector pods bolt on with only a slight modification that doesn't effect them for stock usage, the ends need to be slightly filed where they butt together in the center of the unit.

The linkage shown gives fully synchronized throttles, which at this point I'm not sure is the best way to go, if not I'll go back to the original linkage that staggered the throttle openings some.

For the drag engine this is going on I won't be using IAC at all (my right foot will do that job) so the IAC ports are plugged.

I'll be trying this on a pretty built up 468 with an EBL controlling it, modified to handle 4 injectors. The engine was dynoed at 675 HP with a carb on it.

Unfortunately I don't have a time table yet for being able to try it out, with 2 kids in jr. high school, a business and their crazy mom to deal with my time is pretty tight, it might have to wait until next summer.

If anyone is really serious about trying it out on a loaner basis, get in touch. You would need to supply your own injector housings and injectors, the fuel lines and a regulator and an EBL unit. If it works out for you and you want to keep it, I'd just charge my material cost for it.

Paul T.

Cdeez

tit that is damn cool!

the zander

Impressive titchner, thats damn cool! Out of curiosity what prompted you to choose this over simply running 2X TBIs on a dual carb manifold?

-Z

titchener

Zander, fabricating adapters for a dual-quad manifold is another possible approach, but I already had a Dominator flanged manifold (and engine) ready to go, and this size flange is a pretty good fit for the unit.

Also there's not really any dual quad manifolds available any more that are worth a poop until you get to really high flow rates, except for Pro Stock type manifolds their all pretty old designs. However a Pro Stock manifold would accept 2 of the Franken units, now that baby would fly.

Time constraints and the economic downturn have kept me from firing this thing up on my engine, hopefully I'll be able to do that some day, but I'm still interested in finding someone to test it out in the meantime.

Paul T.

Jinmajay

Wow, that is great! I would be interested in any infor used for the BIN. I used the Edelbrock air gap intake and filter housing. Hooked up lke it was made for it. I also use a couple Trans Dapt carb to TBI adapters (slight mod's).

TT 68

The easy way is to have RBob convert your ECM to an EBL so it can run both throttle bodies, plus you get all the cool features of the EBL.

Another way is to run a piggyback ECM to control the secondary TBI unit. This way you could set it up to be progressive and run around most of the time only using the primary TBI with the IAC.

I thought about going this route and using a PCM from the 94-95 trucks as the primary controller so I could also run the 4L80E functions and get the faster computer to run the engine too.

titchener

Jinmajay, that's a real clean looking setup.

Is this engine running? If so, can you share your experiences on getting it tuned? What HP and RPM range are you targeting?

If you haven't picked an ECM yet I would second TT 68's suggestions on using an EBL, the tuning software is pretty straightforward to use and he can modify a unit for you to work with dual TBI's.

Paul T.

Jinmajay

I am planning to use Bob's EBL and the Modified ECM with increased injector drivers. Bob has given the basic set up instructions. I will have to purchase the modified ECM from him and piggy back my 94 PCM with his. The 94 will run the 4L60E and the EBL mod'd injector drivers will run the engine. I have not done any of this work yet but am planning on it soon.

The numbers show 550 hp and I won't run it over 6K. This truck is AWD so that will take 100 HP off the top so I'm confident she will be around 400 at the rear wheels.

I have never heard this engine run and it's killing me. I built it this winter and I have a load of other stuff I need to do before i will get to hear it run. As with everyone else on these boards, the money has dryed up for now. I have alot of detailed work to do for my project so this will by me some time before I get into the money items again.

I have submitted my stimulus plan to congress for approval last week. My hopes are that they will give some money for my project (to stimulate the economy of course) but I'm not holding my breath!

I posted this photo of the engine on a different thread on 3rdgen:







Fast355 thinks I'm a bit crazy for putting that engine in a "mini" van but I call it a truck.

You can look at my progress at
www.jayjensen.shutterfly.com

Once I get the EBL and ECM in I'm sure I will need a bit of help getting it tuned in. Most people I talk with say that it will be impossible to get everything smoothed out with it.... I like challenges.

Jinmajay

Oh, the real reason I have made an extended cab monster is to take the whole family down the strip at the same time.

People can be so negative. I've had them tell me that this is nothing more than a brick on wheels and that the front end will puke parts all over with that much HP behind it.

SOme people buy a boat, some people drink beer, I am building something no one else has.

TT 68

The Astro van AWD system is identical to the Syclone / Typhoon and can handle 600 hp with no problem. Your transmission is the weak link. There are 10-second Typhoon's out there running your identical stock drivetrain.

What do you think of those new Edelbrock valve covers? They look like a nice option for center bolt heads.

titchener

Jinmajay, that's a real cool looking project. I've worked some with the EBL but not yet with the dual TBI's, but when you start tuning it, start a thread here and I'll help as much as I can.

One open question I don't know the answer to is whether the part throttle response will be ok without having to go to some kind of progressive linkage. I think it would best to avoid the progressive if possible, especially on your dual quad setup.

I like the polished TBI injector pods, I didn't know they would polish up like that. Did you have to do anything special or was that just pretty standard polishing methods?

Paul T.

Jinmajay

Yep, I have had several people tell me about the Typhoon setup and it gives me much comfort. THe tranny is one of those things that I still need to do. I planned on doing it myself (like everything else) but I will need about $400.00 to get the rebuild kit, servo and DVD.

I like the valve covers and wanted the center to keep everything a oil free for as long a possible. One thing I fould out is the True roller rockers will fit under the "short" or stock version but you will need the special "slim" version of rocker. That is the only parts I have returned so far that did not work (rockers). I have found Edelbrock stuff to be somewhat economical and good quality but you have to do research first.

Jinmajay

I'm I hijacking this thred? not meaning to...

Jinmajay

Bob (EBL) did mention that I have what they call a snail-shell style linkage which should help some. It slows down the throttle/petal action. But when you have a light truck (maybe 3500lbs) and two hyper (20 lbs of fuel pressure) and dual tbi's feeding a stroker, it will be hard to control the jumpyness of the truck. Is Jumpyness a word?

I did about two full days of cutting and polishing on the TBI's. I didn't just start by polishing. If you look closely, all the areas that woudl cause restriction are ground down as far as I felt it cousl take. Is it going to provide and performance increases??? I don't know. I just wanted to do it.

I used a cut off wheel to get it down close, then used the HF sanding disks 80 grit then 120. Then I use the HF polishing kit with only the white (finest) grit. Came out prety good, didn't it? THe only other thing I did was to cut the pod gasket down to size after I tightened everything up. You really need ot be careful as the gasket isn't very wide to begin with.

The POD spacer I use was the Trans Dapt one plus a thick gasket. I had to do some major clearancing where the fuel adapters screw in the back.

titchener

Jimnjay, if you poke around you'll run across a post on these forums where somebody did some pretty good flow bench numbers on TBI units, at the standard 1.5" 4 barrel pressure drop, so the numbers compare well to typical 4 barrel carb numbers.

My memory is that a stock TBI unit flowed 490 cfm and doing polishing of the bores, similar to what you have done, bumped that up to 500 cfm.

So a pair of these is going to give you around 1000 cfm. That's a lot of flow which should give you a hell of a top end if your heads and cam can spin high enough to use it. On the flip side, tuning for low speed drivability could be challenging.

Apparently a few years ago one of the TBI parts companies tried selling a product that used 2 TBI units, but never got it running that well and pulled it off the market. But back then the tuning tools and tuning knowledge wasn't as well developed so maybe they gave up too soon.

My rule of thumb is to figure out how much flow you need for a targeted amount of HP, multiply the HP times 1.62, so that means if you divide 1000 cfm by 1.62, a 1000 cfm intake system should be used on an engine capable of around 620 HP. Using more flow that an engine is capable of using (ie if it can't make 620 HP) means you'll get pretty bad midrange performance and you can also get less max HP.

If you are aiming for 550HP you'll be "over carbed" a little, however I do know that the high level of fuel control you have with TBI units (compared to carbs) lets you get away with some things that don't work well with carbs, like single plane manifolds on a street oriented car for example. So maybe with careful tuning your dual TBI system can be made to work on your engine.

There's only one way to find out, and I'm really curious to hear the results.

Paul T.

Jinmajay

My research to this point was that the TBI's with slight mod's would by around 400 cfm (800 total). I will have to go back and take another look. I will be able to do an actual flow test after the engine is running (I'm an HVAC guy with access to a TSI electronic anemometer). I did some figuring on the Mega squirt web site and I don't have the figures with me but I think I will be ok with the stock 350 injectors. I am hoping the the Bob's EBL will make tuning a pleasure. Like I have said before, I am not a gear head, just a dude that has kept the cars running at his house out of necessity. Now that I have grown a bit I have some time and money (not much as this has been three years so far) to do a build. I might have bit-off more than what I should have but it has been really fun this far and I have enjoyed learning.

The induction system should be oversized a bit. The heads are high flowing (Edelbrock Etec 200), 1.6 rockers but the weakest or smallest point is the 220/230 114* cam. It is full roller set up. I really want to have road worthy drivability but still be able to run the motor at a strip. From what I found there is no real way to have really good ends of the spectrum with the same truck. Bob is not really concerned that I won't get it tuned and tell me someone who really knows more about tuning or tuning dual's than Bob?

This stuff takes a bunch of time just to research what is needed to meet your requirements without reparting. I may have used higher $$ parts and from teh pictures it might seem like I have been building for years, but that is just not the case. I am still budget minded and count this as a hobby.

I am in the process of making a custom oil pan and I should be finished with that this weekend. Then I have a bunch of blasting painting before I get back to the engine. Money is the big factor here. So when I get enough to get the EBL, headers, starter, then I will be tuning.

Stay "tuned" because I will need all the help I can. If there is anyone that is knowledegable around Columbia, MO that wants to pay a visit when the time comes to start and tune- send a IM...

And if anyone has estimator software and have the time and is willing, I will give them all the build spec's to see what the HP actually comes out to.

Jinmajay

Oh, This block has two bolt mains and i haver regeared OEM front diff so I think the motor would potentially have too much HP for the application.