383 build using a TBI-please help
 

I have been involved in other forums for a number of yrs.One being one that deals with Astro vans.I think I understand answering the same question about a topic hundreds or thousands of times over the yrs and this one I am asking I am very sure you guys have dealt with this topic over the yrs a number of times.Great sites like this one does have tons of ref threads.I have done some research on this forum and decided I needed to post this thread for more specific to my build.Kind of suffered from some info overload which is a compliment btw.It isn't a car,it's a custom Astro van,but a 383 build none the less and you guys have a great rep on your knowledge of the EFI systems and on the TBI's.I am open to learn and suggestions.Here is a outline of the build and a picture of a photochop of the van.

I need help in planning for a EFI for my SBC 383.Here is the outline for the build:

1995 L31 roller block

.030 over

5.7 rods Scat rods profiled for stroker with 7/16 ARP bolts

3.75 Howards track smart crank

Icon 18 dished pistons

decked 10 down

World S/R heads 67 cc heads with 170 intake runners.

Static compression ratio 9.2

Hyro roller cams being considered:

GM part number 14097395

288/308 duration @.050

196/206 with rocker ratio 1.5.1

431/451

Lobe centerline 109

OR

Erson cams

Part number E11980

Rpm range 2200-5200

Duration 272/280

Duration @.050 218/226

480/480 rocker ratio 1.5.1

lobe center 108

OR

Part number E119847

Rpm range 2500-5500

Duration 286/294

Duration @.050 226/234

548/540 with 1.5.1 rocker ratio

Lobe center 112

It is going into a custom conversion high top 1989 cargo Astro van who's wt is in the neighborhood of 4,000lbs with a 700R4 tranny and a Ford 9" with a 3.70 rear end gear and 29" tires.Primary use is to tow my small vendor trailer over the road with a trailer wt max of 3500lbs.Then with out the trailer to occasionally put a smile on this old time drag racer on the street lights only.No drag racing race track use.Want to get max gasmileage and max torque.

Ran the build on a computer dyno with using a 600cfm carb application and got about 470 to 480 ft lbs of torque@ 3500RPM and 350HP@ 4400RPM.

When the plan for this build first came about-the intent was to use the TBI/harness/ECM from the 1995 truck the engine came from.But I am told that with a MAP sensor it will not work.That I need to use a mass air sensor.The question I have is there a conversion for the mass air flow sensor I would use??.

Things I don't want.Laptop on the passenger seat for constant changes.Any risks of a injector system washing down the cylinders.Kind of a plug and play is what I am looking for.Reliability!!!!.

I am somewhat aware of the Edelbrock systems,I have looked at Fast(I think at first they try to be the cheap possibility,but in the end the parts end up cost about the same as anyone else.Could be totally wrong),Holley,Mass Flo injector systems,(yes I read the thread here about them).

I am open to any and all suggestions.Please and Thank You very much.

Gary

The photochop picture which the graphics aren't done yet and the color will be abit darker.Vans nickname is Ole Yellar.You'll see one of the custom aspects is a slider door delete.

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Re: 383 build using a TBI-please help
 

Why not a HT383?

http://sdparts.com/details/gm-perfor...parts/12499101

Re: 383 build using a TBI-please help
 

Because I already bought and own most of what I listed.Actually about a yr 1 1/2 ago I bought a donor Astro van that had the V8 L31 converted into it.That meant I got the engine mounts,running 1995 short block 350 crate engine with supposedly only 100,000 miles engine,1991 truck 700R4 in need of a rebuild,computer,converted harness,and a TBI with 65lb injectors lifted,exhaust manifolds,exhaust system,etc.The game plan at that time was to swap the engine into the more desired body style of a high top cargo.The engine suffered while in the donor from a high idle issue and I later found loose intake bolts especially in center hard to get to bolts loose.(kind of a hack job)I wanted to aleast reseal the engine and check the bearings before I swapped it.The rod bearings where worn badly and well at that point we decided a 383 was the path to take.I do have a fair amount of money invested already into this build,so to change now isn't possible.Thank you for your reply.:thanks:

When the donor engine was in the sub frame pictures and spare engine mounts from a company called Jag's That Run.

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I like the idea of a four barrel 2" 454 TBI because of the extra injectors and I am thinking better fuel distribution.I have read the thread about external injector drivers.I have been warned by guys who are mainly carburetor background that TBI's without a Mass Air won't work.I have a sense that there is a conversion from a Map to Mass air,but don't know the details.I have read about increasing the fuel pressure because at the top end of the mechanical/volt limitations to fire the injectors.In the same hand(and again from a unqualified carb guys)to be very careful not to over fuel at idle and wash down the cylinders ruining a engine.I am here to learn what is the right TBI set up for my build and I am saying a TBI because from my understanding they can be even more simple than a carb.

So guys please help me.:help: I will eternally grateful.

I am going to be 64 yrs young with a background in hot rods.The EFI's is new to me,but I am certainly willing to learn.A carb for this build isn't at all what I wanted for a number of reasons.

Re: 383 build using a TBI-please help
 

I would say those world heads are holding you back and the first cam is small.. the second and third choices are better. You can fuel it with the big block injectors and bump up the pressure, but theres no way around it that engine will need to be tuned. The laptop will be on the pass. seat and the computer will be sitting on the floor.
I don't see why the MAP system won't work, If you have the 95 Pcm I would just use it, its a good one.. or you can get the EBL its a nice all in one tuning aid but either way you will need a laptop and some time.

Theres a guy on here.. Fast355, hes the man when it comes to vans and tbi. I would search around for his posts.

Re: 383 build using a TBI-please help
 

no tbi setups came with MAF's. That is a specially designed unit by Dimented24 is it not? the 454 tbi is not a 4bbl it is a bigger 2bbl that is it. That is the unit you should run, but you may have to get bigger injectors. Injectors plus makes bigger injectors than you already have. deffinately have to do custom tuning EBL flash. Thats about all I know about your combo. Of those cams you listed the only one Id run is the 3rd option. Its more of a fuel injection cam and will be easier to tune.

Re: 383 build using a TBI-please help
 

Thanks for the reply.I am hoping Dimented24 and the others from the sticky sections will join in helping out on this thread.I did read about Mass-Flo injector systems to find they are what seems to be over priced using a old Ford Mustang system.The RPM range on purpose is for torque with a peak HP at only 4400.That is the reasoning for the only 170cc intake runner to try to keep the volume up.Of course again I am open to suggestions that relate to a TBI and system.

Re: 383 build using a TBI-please help
 

The next time I will be at the shop will be Weds and I will grab the numbers off the two ECM's I have there from the donor V8 van.Maybe that would be a good starting point for this thread.

I am still hoping to attract more support and advise for the thread.I am going to be 64 yrs old and this build is my last(hopefully my best) and apart of a business that will support my retirement.I is very important to me because of that.

Just in case anyone is wondering how serious I am about this and the other projects I need to get done,here is a picture of the shop I rented and developed with equipment to work out of.It is the left side of this medal pole barn.

Attachment 388924

Attachment 388925

Re: 383 build using a TBI-please help
 

Those guys need to lay off working on carbs and let the fuel fumes leave their heads. EFI tuning has come a very long way since Superchips and ADS were about the only "CHIPS" out there. The 1993-1996 TBI PCM the 7427 specifically will run just about anything that makes any vacuum at all. As long as you have atleast 12-14" hg of vacuum at idle making a fuel map will not be overly hard. Once you get under 12 in/hg tuning gets a little more complicated but I have tuned a speed density (MAP) car that only had 8 in/hg in gear at 800 rpm.

Re: 383 build using a TBI-please help
 

Fast355.Thanks for your reply.I do have some questions for you.

Given the parts I mapped out.Which would you use for a cam for ease of tuning and the best for torque??.

Because of it being a additional 38C.I,would a speed density system be in my best interest for the long term??.part numbers,maybe some ref links??.

:thanks:

Re: 383 build using a TBI-please help
 

For torque and towing you would want around 9:1 compression, SWIRL PORT HEADS, dual plane manifold, long tube headers, 6" connecting rods, and a cam with short duration, steep ramps, tight LSA, and as much lift as you can run, probably advanced 2-4* and preferably 1.6:1 roller rockers. With a short duration roller cam you can run a tight LSA and still have very little overlap.

I would stay with speed density.

Re: 383 build using a TBI-please help
 

For the record the engine casting number is 10243880-1996.

Fast355 if you look at the beginning of the thread the static compression is set at 10 down from the deck with 67 CC heads for it to be 9.2.The Howards steel track smart crank is for the Icon dished pistons which are for scat 5.7 7/16 ARP bolt profiled rods.

So I was moving on now with mapping out a game plan for the EFI and cam.I get the sense that mass air flow systems are more accepting for lobe centers under 112.I don't think I have ever considered a cam over a 230 duration,but I have looked at 108 lobe centered cams.

I wanted to add that the logic for the 5.7 rods was we wanted for the most part keep the pin hole out of the ring lands needing ring spacers.

Re: 383 build using a TBI-please help
 

All I have to add is that speed density works great as long as you are making decent vacuum, LSA does effect overlap but so does duration. Short duration and tight LSA builds midrange torque you need for towing. I have a 287 CID engine making 340 HP and 360 ft/lbs of torque, running on speed density, runs at 10.25:1 compression and has cams that spec, 254/260 @ .006, 218/224 @ .050, .502/.520" lift, and 110 LSA, makes about 14 in/hg of vacuum at idle. Was not hard at all to dial in the tuning on.

Re: 383 build using a TBI-please help
 

What do you think of the first cam I listed from Erson??.

What you suggest I use for a EFI system??Part numbers etc.

That part I admit I am a total newbie need to be taught.

Re: 383 build using a TBI-please help
 

Guys here is what I got from the research I have done in a summary.

Mass air flow for my 383 is better.The bigger the sensor the better.

Wide band is a system that I should use

Heated 02 sensors is certain a part of the system for a 383

Thing is when your on your own,you need good folks like your guys to connect the dots or tell me to get that yr part and do what with that etc to learn why it works the way it does.Then it all of a sudden becomes a oh now I understand it.No one was born knowing the EFI systems and of course I wasn't either.:confused:

Want to give credit to Fast355 for the value time he spent with me.:thanks:

Re: 383 build using a TBI-please help
 

What do you really want the engine to do? Tow and get good economy?

If thats so, then what you want is a cam that has relatively short duration and little overlap. Any excessive overlap will just cause bleed down at lower RPMs where you tow, and drop your dynamic compression.

Another good head choice are vortecs or vortec style heads. That style of combustion chamber generates good swirl, requires little timing, and has better intake port flow than other heads. There are also hybrid style heads that use the vortec style design, but accept a standard intake manifold. A stock style cam with good flowing heads can make just as much or more power than a more aggressive cam with lower flowing heads. The end goal isnt xxx duration, its to have enough flow capacity to fill the cylinder with air at a given RPM.

As far as the cam, I like the second the best, with the exception of the LSA. That may be a bit too close. Something with similar specs, but with a 112 or 114 LSA would probably be ideal.

I would hazard at saying something like Comp cams computer controlled 266HR-14 or maybe something a tad bigger like the 270 since its a 383. You dont want to get too carried away as your using it for towing. Same thing goes for the lift as well. High lift with hydrolic roller lifters means that you need to run heavy springs or a rev kit to run the engine at higher RPMs. This places more load on the valvetrain and cam bearings, which can shorten their lifespan. Not really an issue in a performance street application, but something that will run for hours on end it can be an issue. I ran into this when running a larger flat tappet with heavy springs. The higher loads and less than perfect journal finish on aftermarket cams nuked the front cam bearing.

For maximum reliability, you may also consider running aluminum alloy cam bearings since theyll handle high loads much better than babbit. The downside is that they require greater care and attention to make sure theyre installed properly and the cam is straight with the proper journal finish. I put speedpro silicon/alum. ones in my current build, and Im having much better results this time around. Same goes for the bottom end as well. Aluminum bearings are the preferred bearing material now for GM crate and production engines. Again, though, it requires a good finish and proper clearances as aluminum will not give like babbit if the clearances are off.

As far as the springs go, comp has beehive springs that use a small retainer. These take a lot of load off the valvetrain, so you can run a lighter spring and still get the same results.

Re: 383 build using a TBI-please help
 

As far as the type of EFI goes, speed density will work well provided the following conditions are met:

1) The engine should make good vacuum.

2) The intake should be a low rise or stock style type with heated jackets. No Airgap style intakes or anything like that.

3) The intake air temperature should be uniform. That means no cold air intakes. An open element or stock style air cleaner will work best.

The goal here is to keep the incoming air temperature more or less uniform so that you dont get a lot of drift from fuel dynamics. The fuel pulls heat out of the incoming air charge and it can dramatically change the density of the air.

I made the MAF system as I was running a performer RPM airgap with a cold air intake with TBI. It had to work well in both the summer and winter. SD couldnt even come close to working right with that type of setup. The intake would literally go from being ice cold in the winter to 200+ deg F in the summer, and everywhere in between. This dramatically changes the incoming air density in ways that the SD logic cant handle.

Re: 383 build using a TBI-please help
 

Could I back up here with some questions.I have been told that a MAP won't work at all on this 383 regardless of cam choice.

That although guys try to run larger injectors with increased fuel pressure for the top end,the possibility of a over rich condition is very likely at idle that wash gas into the oil ruining the bearings.What I found on this engine was during a bearing check this 100,000 crate short block had bad rod bearings.The previous owner has just extended the wires from a Astro wire harness for the injectors,put in 65lb cop car injectors lifted,the ECU from a 1995 donor truck,never burning a chip.Makes me think that was the cause for the short life of the rod bearings.That scares the heck out of me.I do not want to take that kind of risk.

Both of the above might be total misinformation.It comes from carb backround guys.I hope you can clear up the confusion.I have more questions,but these two basic questions answered sure will help.

Thank You.

Re: 383 build using a TBI-please help
 

Just one point for clarification.The parts chosen for the engine build is the results of a yr's research now coming here to finalize the EFI/cam selection.I just lost a long post to explain the how and why we came to those choices.I am going to set back and read your inputs while I cool off.:mad:

What do you guys think about using a carb for break-in on the engine and then after that install a EFI to try to tune.??.

One point to clear up is the Howards crank requires "H" bearings and we are using King bearings.

Re: 383 build using a TBI-please help
 

383's can and have been run off MAP, as has been stated it all depends on what sort of vacuum is pulled @ idle. Everything needs a tune, even stock stuff. If you're taking a long time to post something, always hit "preview" instead of "sumbit". I'm not going to get into details explaining why but you shouldn't get burnt again with this method.

Re: 383 build using a TBI-please help
 

Thanks for the tips and especially the one on posting.

Re: 383 build using a TBI-please help
 

Not trying to start a fight or be rude, but if you do not have the engine built yet and it is still in the planning stages, S/R torquers are about the last choice I would run. They have no redeeming qualities in my book other than being a little thicker and therefore more crack resistant than a stock head. If you want to run that much compression while towing, you need an aluminum head plain and simple. Brodix IK180 is what I would run. Smallish ports, great flow, fastburn chambers, and great heat rejection out of the combustion chamber, all of which help keep detonation to a minimum.

I tuned a BUILT 408 in a 1939 Chevy on a MAP system with Dual TBIs on a tunnelram. Idle vacuum was a mere 8 in/hg, but I was still able to make the engine and 4L80E transmission behave. Took some effort dialing in the TBIs, but the result was well worth the wait. I ended up blocking one of the IACs completely and running a non-progressive 1:1 linkage with all 4 injectors firing at the same time. Couldn't keep the tires from spinning on the street.

Re: 383 build using a TBI-please help
 

Hey Fast355-Check it out.bore is 4.030-stroke is 3.75-head gasket is .040-deck is .010 down-chamber is 67cc-pistons are -18 dished which equals static compression ratio of 9.21.Not wanting to be rude either.

This is the link.
http://www.csgnetwork.com/automotiveconverters.html

I want to deal with the use of aluminum heads here.The background I have is a swap meet vendor for about 17yrs.Not that by any means I know it all.In that time I have seen more low mileage aluminum heads that where in serious need of a rebuild of all brands used on the street.Fact of that kind of history is you don't make any money unless you know what to look for.And we surely have made money.They are great as a head for toys,but not for a long term mileage engine that I am building.It is very true that aluminum dissipates heat faster and that will allow a higher static c/r.But it is also true in doing so it lowers that c/r about one point.So let's say your at 9.98 c/r and use paying more for a aluminum head that lands you now at 8.98 c/r.The standard of this build is this engine will not be below 9.0 but will not be near 9.5.Mainly we don't want timing pulled out of the engine and pinging.

The use of 170cc intake runners seems small,doesn't it??.We ran this combo on a computer dyno using a 600cfm carb.By keeping the runner on the smaller side with 202 valves we are tailoring the torque peak at 3500 rpm by keeping up the volume.480 lbs of torque.The peak hp was at 4400 rpm.350hp.Again these vans need torque more than anything to move a vehicle of over 4,000lbs.The OEM roller retainers and lifters do not lend themselves to not much over 5,000.In fact Comp Cams offers a fix for that very reason.I have a very good friend who owns a single turbo charged Camero.Those don't have much of a cam in them and he just once missed a shift with a rev limiter set at 5300 and ended up with collapse lifters to replace.

Use the same link for mph at what rpm.Well at say 5000 rpm with a 700r4 and a rear end gear of 3.70 with a 29" tire.That is 155.47 mph ideally.Now these Astro's are a pc of plywood box with the aerodynamics of a rear end of a pig:eek:.I know that is old boy isn't going for that ride.LOL.:lmao: Actually I don't know of every many people that consistently had their Astro's over 100mph.They kind of float on their own at that point.

Fast355 as I said I am in no way trying to be a smart guy or rude.We are attempting to build a broad early torque band and everytime you move up the runner size,your moving the torque band up the rpm range as well.

The general rule of thumb has been to multiply C.I. x .5 for a intake runner size.So you say aaa-then a 383 x .5 would be = to 191.5.And that is true except for the consideration of the torque/hp peaks.


We need to cam/and build a efi that will support that broad early torque band.It does seem that everytime we find a easy tune lobe center like 112 or 114 the other specs don't fit the model of a early torque band.:doh:

Re: 383 build using a TBI-please help
 

I don't know why I didn't post pictures of the pistons before...

Attachment 388796

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Notice how they give a ring end gap for towing.We add .003 to .005 to that.

Re: 383 build using a TBI-please help
 

That one point thing is an old wives tale. Its true that aluminum does conduct heat faster, but its not an easy linear relationship. There are a lot of factors that will determine how much heat escapes out into the head, such as the piston dwell time, the rate at which the mixture burns, the amount of carbon build-up in the chamber, the conditions in the chamber, etc., etc. Most of the heat is kept away from the chamber walls, anyway, by a static boundry layer of gasses that act as an insulator since the heat can only be transferred via conduction rather than convection there. They do have an effect, but I dont think its nearly as great as one point. Thats a considerable loss in efficiency which would probably overwhelm the cooling system if that much heat really did make it in. I think one of the main reasons you can run a little more compression on aluminum is that its at a much more uniform temperature. With cast iron, its easier to get hot spots in the chamber.

Re: 383 build using a TBI-please help
 

Also, why run forged pistons in a tow engine? IMO, unless you plan on towing with your foot to the floor the whole time, youd be better off with hypereutectics. Forged pistons need A LOT more room to expand than standard pistons. Those will tend to slap a lot when theyre cold, so you will need to take extra care during cold operation.

Even my GM with stock hypereutectics has a good ammount of piston slap when its cold. GM includes special logic in the PCM to alter the timing and provide some additional protection for the pistons until they warm up and establish the proper clearances.

You can probably run them without issue, but theyll need a little more attention than yer basic cast pistons operation wise.

Re: 383 build using a TBI-please help
 

MAP will work fine provided you run a stock type setup induction wise and dont run a cam with overlap. You probably wouldnt notice the difference between a MAF and MAP setup. Its only when you get into cams and running the TBI without any heating in the induction that MAP will become an issue.

MAP will be a little more time consuming to tune, and wont adjust as well as MAF to changing conditions, but it'll work reasonably well if you tune it right. Since this is a tow application, the closed loop O2 PID will take care of most of the fueling corrections, anyway.

One thing I will say is that you dont want to use your stock ECM. Use either a later PCM, or use a modified TBI ECM with EBL. The stock ECMs are pure crap from an engine management standpoint.

Re: 383 build using a TBI-please help
 

You have to be running pretty damn rich to thin out the oil with gas. Id suspect that you score the cylinder walls, too, if it was a viscosity loss that caused the bearings to fail from gas getting in the oil. More likely it was a finish/clearance issue, lack of maintenance, or just heavy use that caused them to fail.

Re: 383 build using a TBI-please help
 

Icon (well really KB) did something interesting.They are running a offset pin to limit slap.

Re: 383 build using a TBI-please help
 

Should I be considering a tune port over a tbi??.What is the merits of each??.Here is some of that newbie EFI stuff coming out of me.Sorry I have to ask.EBL??.:doh:

Re: 383 build using a TBI-please help
 

I agree with you on aspects being hot spots,piston dwell,rate of fuel burn,etc.While I worked at the Chevy Tonn,NY engine plant in the dyno rm we ran comparative tests in exactly alike head configurations with the only difference being materiel changes(iron vs aluminum) we could track those losses.By back tracking the results that is why I said it was about 1 point.The other source that supports that is a site that over all is a great resource for a number of topics you might want to check out if you don't know about it yet.

http://www.enginebuildermag.com/

Gear more towards the guys who are in the business of engine building and some really good common sense tips and tricks.Gives you insight to changes in the business too and as a consumer that can be very helpful.

Re: 383 build using a TBI-please help
 

That is a very good point about the walls.They where not scored and just had the normal slightly out of round wear.What do you think about me using a carb set up during engine break-in??.I have been told even in the best case with a EFI there is going to be trial and error to tune it.

BTW-thank you.:thanks:

Re: 383 build using a TBI-please help
 

The thermal efficiency is fairly non-linear with respect to the CR. Did they calculate it in terms of efficiency? That will give you a better idea of what the actual losses are. A 1 point CR loss at 8:1 will have a much greater impact than a 1 point CR loss at 12:1 on the efficiency.

Re: 383 build using a TBI-please help
 

If you get an 8625 PCM, you can run MAF and SD TBI and TPI without having to repin anything (other than adding a MAF). Those PCMs have a lot of inputs in them. The only thing to keep in mind is that the MAF setup doesnt support EGR or CCP as its a performance application.

For EBL, see www.dynamicefi.com

The TBI will work fine for your application since its a large tow engine with a fairly narrow RPM band.

Re: 383 build using a TBI-please help
 

I am reading the ref link and bookmarked it.Thanks.

Re: 383 build using a TBI-please help
 

Another EFI newbie question.Again thanks for the link.There is alot to study there,but all I need to learn as well.

So-does that mean I will be tied to a lap top for life or once I program it,will it be set it and forget it??.

Thanks

Re: 383 build using a TBI-please help
 

Some off topic info to share here.The main theme of this 383 build is to over build it for long term durability.I got the Howards Track Smart 4340 3.75 crankshaft today.It has been a longtime coming and I am very excited/proud to have it.Certainly a major step towards a rotating assembly.

Attachment 388665

Attachment 388666

I just wanted to share with you guys.I will send it out to the machine shop to have it checked out to be sure it is 100%.

Woo-Woo!!.:D

Re: 383 build using a TBI-please help
 

Will probably need too play with the laptop for a wile to get it perfect.

The crankshaft in the pic is for 2 piece rear main seal, does it fit your '95 block?

For parts selection, it can help to play with some engine simulators softwares too, if you haven't already. http://www.summitracing.com/parts/CCA-181501/ http://www.summitracing.com/parts/CCA-186011/ http://www.camquest.com/

Re: 383 build using a TBI-please help
 

I will be buying a seal adapter for the crank,"H" bearings and a 2pc seal flexplate.

Thanks for the links.

Re: 383 build using a TBI-please help
 

It wont be a tied to a laptop for life, but the TBI will need some tweaking as the weather changes. Since its a wetflow system, the fueling will drift a bit as the temperature changes. SD wont correct for this. The O2 PID will, but it wont help at WOT. If its a little off it wont be a big deal, but if the fueling does go more than 5-10% above or below where you want it, you should retune for the conditions.

The later SFI stuff is a set it and forget it affair, but its much more involved to set it up.

Re: 383 build using a TBI-please help
 

Thanks for the continued support of this project/thread.I'm trying to learn from the posts of other threads,stickies,and supplied links as fast as I can retain the info.It looks like I am missing out on a group buy in Aug.Thing is I don't know yet for this build what to get.Maybe someone could shed some light on that for me before the deadline date.

:thanks:

Re: 383 build using a TBI-please help
 

Gary you asked about the EBL, the site link was already posted. www.dynamicefi.com

read about it. If you decide you'd like in. Thier is a group purchases forum down below with a thread on this, post there and i'll add your name to the list

Re: 383 build using a TBI-please help
 

I am guessing I would need the four barrel one for this 383??.

Re: 383 build using a TBI-please help
 

Well I am taking about the upgraded version

Re: 383 build using a TBI-please help
 

the p4 runs multi port fuel injection. I dont really know anythign else besides that. If you have any questions about your specific application you can PM Rbob on here. He is a moderator. It is his design. You'll see him all over the site, but especially in the DIY tuning board.

Re: 383 build using a TBI-please help
 

See where it says which flasher to use??.I clicked on that and saw the four barrel improved system.It's that one that I am talking about.

Re: 383 build using a TBI-please help
 

yup i see that

Re: 383 build using a TBI-please help
 

I doubt you will need a 4 barrel TBI for under 500fwhp.
Not sure this 4 barrel TBI was ever completed, but still good info https://www.thirdgen.org/forums/tbi/...anken-tbi.html

A 50mm bores TBI TB should flow more then this 383 needs and a pair of #80/hr injector @ 22 psi should be good for 400fwhp.

For 2 TBI injectors EBL flash and for 4 TBI injectors you would need to add the 4 injector "upgrade". The word "upgrade" does not make it better, just set up to run 4 injectors.

Re: 383 build using a TBI-please help
 

Thanks for clearing that up for me.I'll read the ref thread.

Re: 383 build using a TBI-please help
 

PM sent to Rbob.

Re: 383 build using a TBI-please help
 

Could I be asking the wrong question here??.Wouldn't I be better off using a TPI over a TBI considering guys with a TBI are running bigger injectors and a higher pressure to compensate for a two barrel over what would seem a more per cylinder exact fuel distribution with a TPI.Does TPI's suffer with a air issue??.

I an trying to get to a place where the induction is more than I need and the computer is controlling the fuel/air ratio.

I fight with myself knowing a 108 lobe center gives in part a lower torque band over a 112 or 114.The other thing is knowing the GM hydro lifters do have a limited RPM range.Of course a duration under 230 on the cam.We found with a computer dyno and a 108 a torque peak of 470/480 range at 3500 rpm.It has been real hard for me to give that torque peak point up.

I have more questions,but I'll wait to see what you guys say.