has anyone ever built a 383 or 400 TBI motor?

 

GM makes a 454, and there are a few people on here with a 383. Someone at my school runs a 383 stroker in his LO3.

 

I have a TBI 454, and GM built it.

 

i think there is a 502 as well? VAFPR . i was of belief it was a marine application but would work for car/truck as well...

 

i didnt mean like Gm built im talking like High performance Built.

 

Do a search for "r90camarors" he built up a 383 TBI. Search for him and check his sig. you'll see the build.

 

I'm building a 388ci now. I've got a .060 bored 350(#3970010), Scat 3.75 stroke crank, Scat 5.700" floating rods, Speed-Pro 10.5:1 pistons, Scat flexplate, Scat balancer, Comp Cams 224/230-503/510-112*
Thats all I've got so far. I'm still waiting on the pistons & cam to arrive, then the shop is going to test fit and do some clearancing and then it all off to get balanced. I'm letting the shop put the short block together then I'm finshing it off.
When finshed I'll be running a 700cfm Holley 4bbl TBI.

 

Hey chevypower, are you going to have to put in a new wire harness for that 4bbl TBI? I bet that thing is going to be nice!

 

.

 

Here's two examples of dual TBI:

http://impalassforum.com/cgi-bin/ult...=001148#000011
(see Draggin Wagon -- then search for his other posts).

https://www.thirdgen.org/techbb2/sho...mercury+marine


Tom400cfi has (had?) a 406 under his Crossfire intake (using the dual single-bore TBI units). The 383 and 454 car(s)/trucks have already been mentioned.

 

No I'm using the stock harness. I got the 4bbl TBI from Howell. They rewired it to work with the factory harness.

 

I hope their not leading you down a dead end street. Howell is saying that they can make a 4brl tbi work using the stock ecm without extra injector drivers or are you swapping ecms as well? Are you going to use the 749 ecm?

Steve

 

I have a 94 GMC Suburban that came stock from the factory with a HIGH output 7.4L 454TBI. What was even cooler was GM actually called my Father up right after he bought it and said "We understand you just bought one of out higher performing 454s, and we want to do an experiment on it. We are going to put a better exhaust system on it we've been toying with. We'll do it for free! If it works it will increase your HP/TRQ by about 5%, and if it doesn't, we'll fix it."

Needless to say he agreed to it, and it worked WONDERFULLY. That truck it a BEAST.

Bruce (90RS305)

 

I'm using the 8746 ECM, no extra drivers. They say I'll need a new chip, they sell them too(don't know if I'll use there chip though).

I talked to a guy a while back on here that got some help wiring a 4bbl TBI from Howell. He used the factory ECM too.

 

I recently pulled my mid-high 13sec 350TBI motor and an currently rebuilding it as a 383 with AFR195's, roller cam etc...
I am keeping the TBI on top and hope to crack a 12 sec pass with it..

 

So.. the stock ECU can power more than two injectors? I notice the ECU Mercury Marine was using also only uses two injector driver channels..

Did they wire the injectors in series, parallel, parallel with added resistors... ? More info!!

 

.

 

Easiest block to start with would be an L98 or LO5 block.. one piece rear main plain old 350 SBC.. then you toss in a 400 SBC crank, usually using today's "383" specific cranks which you can find in Jeg's, Summit, or any other dealer with an excessive parts listing, or an entire rotating assembly via Eagle, Hardcore, etc.. Specific pistons with a height to compensate for the increased stroke (.27" extra stroke, .135" less piston height), to make sure you don't slam them into your heads..

"stroke" is a reference to the amount the crankshaft rod journal moves between top dead center and bottom dead center. 305s and 350s use a 3.48" stroke crank, meaning the up/down movement of the piston covers 3.48". A 383 uses the stroke of a 400CI small block of 3.75" without the additional .125" bore of the 400...

Or, for a motor with less piston Gs and thus easier to wind up to higher RPMs, take the 4.125" bore 400 and drop in a 3.48" 350 crank for a 377 destroked motor..

And nowadays there's even stroked 400s, which, using the stock 4.125" bore and a 4" stroke crank, convieniently end up as a 427. An added .125" bore, you've got a small block 454 of the stock bore/stroke of a big block (currently in very limited production, and I'm personally quite fearful of their .200" cylinder wall thickness)

 

i thought, to build a 383, you had to have the 400s 3.75 crank as well as its 6.0 in rods, rather than the 350s 5.7 in rods. or is it just the 3.75 crank and the 5.7 in rods? am i correct about the 400 even having 6.0 in rods?

 

A stock 400sbc used 5.565" rods.

Steve

 

 

Just to reply to the above post about running dual tbi's off of a stock ecm without an injector board. It won't work. You have to have an external driver board, no way around it. I don't think the injectors will even fire without it, and if they do it will burn up the drivers in the ecm. The injector driver board route is the way to go. It takes a good bit of time to tune and if your running a fairly mild motor you may have trouble getting it lean enough at idle. There was a guy offering to get some injector driver boards made a little while back, try a search.

As for what is required to feed a 383......I'm running a fairly warm 355 that is making around 300 to 320 hp with a 454 tbi and 75 pound injectors. I'm up to 22 psi of fuel pressure and I really need another 2 or 3 pounds to safely have enough fuel on the top end. So in my opinion you will need 4 injectors to feed any kind of a hot 383. If you read around I'm sure you'll find that is the general consensus. Also the 2" throttle bore's on the 454 and holley tbi's are about maxed at around 350-375 HP, any where past that and the TB will be a restriction.

Just some info I have picked up hanging around here for the last 2 years.

 

Monte? 75 lb injectors? i am getting conflicting info on injector size. i have a new 454 dual TB awaiting install. came off a 1994-1995 pickup 454 cid. i thought old 454 was 85 and new 454(1992) was 90 lb injectors? are yours GM? i ran 90lbs at 9 lbs and at WOT was 12/1 on WB02 on dyno. it seems i have capacity to spare. 222 hp at rear wheels. 275 hp engine? over 300 hp is within capacity easily IMO.

 

I ran mid 13s with 84 Firebird with a 355, on TBI. My 91 truck with a 454 ain't a race car, but makes a boat load of torque from off idle, on up. 5,000# trailer, half a dozen long blocks, 70 MPH, A/C on, and does it till, I get tired. Yes, I have a bit of time in the chips in both.

Using one of the later *E* series tranies, and PCMs would be the best place to start.

To run more then 2 injectors correctly takes a remote driver board to be able to handle the proper amount of current 4 injectors need. There are Mickey Mouse ways around that, but I never got them to work, correctly.

 

.

 

You can get higher revs out of a destroker. All it really does though is screw up your powerband...
The way you get a 377 out of a 400 is making the cylinder travel less distance (smaller stroke), whereas making the overal displacement smaller. The cylinders and the pistons are still the same size. This is the same with the 383, only you make the pistons travel a greater distance (larger stroke). You can buy stroker kits for various performance compaines. eBay always has a large selection of pre-stroked motors for sale as well.

Someone please correct me if I am wrong, but I don't think I am. I've been looking into a 383 myself for a while, and this is some of the info I dug up. Check out this thread, too. It may help:

https://www.thirdgen.org/techbb2/sho...51#post1421951

Bruce (90RS305)

 

I apologize if I seem to be repeating myself or Bruce

I think you're really missing this "stroke" concept.

As the crank spins, the piston moves up and down. This, multiplied by the area of the bore of the cylinder, generates displacement per cylinder. By changing the crankshaft, you can change the up/down travel of the piston, thus changing the displacement of the cylinder, without changing the bore at all. More stroke == more air/fuel in the chamber + more leverage on the crankshaft == more torque. Less stroke == lower piston Gs == higher RPM tolerance == more horsepower.

The advantages of each is a disadvantage in the other. Let's look at the full example set of the 302, 327, 350, and 383. All use the same 4" cylinder bore.. but the crankshafts each use vary greatly. 3", 3.25", 3.48", 3.75" respectively. Is any one motor better than another? Not particularly. Each has its strong points and its downfalls.. each has its little niche in the small-block chevy ecosystem. 302s can wind like nobody's business, but they're small.. 327s are larger, and wind relatively like nobody's business, and alot of people like them for this. the 350 has a fairly average bore-stroke ratio and is a trade off leaning more to the torque side, and the 383 is just a torq-monger than isn't usually going to see reliable duty over 7000 RPM (they exist, but.. ick. obnoxious piston Gs)

Bore area = Pi * Radius of cylinder ^ 2 (12.56si on 350)
Stroke = piston travel between TDC and BDC (3.48" on stock 350)
Displacement per cylinder = bore area * stroke (43.78ci)
Engine displacement = displacement per cylinder * number of cylinders (349.84ci)

 

Ronny: I'm not completely sure what year my 454 tbi is off of but there were 454 tbi's with the 75 pound injectors. I'm currently running 21 psi and if my memory serves me correctly that calculated out to be around 105 pph. I have just now gotten my motor to run up to my 6000 rpm redline. I really need to run a little more pressure because I'm still going static right at 6000. So i'm pushing the duty cycle a bit.

It does sound like you have the bigger injectors but I would check the part number or the paint marks if your injectors still have them to be sure. It would have saved me alot of time if I hadn't have ASSumed that I had the bigger 90 pph injectors.

To everyone considering a big inch motor under a tbi. You are seriously going to be running out of fuel at around 375-400 hp even with the 90 pph injectors, and this is even if you turn up the pressure to some where in the neighbor hood of 25 psi. I got cought up in the math and though that there was now way my motor needed more than the 454 injectors at 9 psi and chased my tail around for weeks. I was wrong I needed more than double the pressure in order to feed my motor. Also the 2" tbi is going to start costing you HP at around 350-400 hp too. Sure you'll make more hp but the tb is going to be eating some of it.

I am by no means the final answer on this subject but I have read all the arguments and tried it in the real world and have gotten a decent feel for what the 2" tb and bigger injectors can handle.

 

.

 

well the 377 is gonna make more tq/hp than a 350, a 383, will make slightly more tq/hp than a 377, a 400 is gonna make more power than a 383, etc. Don't listen to any of the bs you hear about destroking. It's simply retarted and defies all logic. Go with the most cubic inches possible.

 

^agreed. I think you need to establish what your ultimate goals are with your car/engine. What kind of horsepower are you looking to achieve in the end or what kind of ET's are you looking to get? That will help decide what the best engine for you would be.

 

.

 

The 3.75" crank to stroke a 400 to 427 is not a production crank. Aftermarket only. http://www.theengineshop.com

The point is generally rather moot on the street. To take advantage of a 302 or 327's true rev capabilities requires an obscene cam, usually in autocross or stock car racing where launch torque is the least concern. Even the 383 can be given a cam which would give it horrible street manners, and still hold together. Would you want to do this? Not particularly.

I was merely explaining the point of destroking to help you better understand the concept of stroke as a whole. In a street/strip motor, torque is your friend. Both involve low-rpm launches.. with the 383 or 427. You can still push over 1hp/ci, and have truckloads of low-rpm torque of the variety that makes it absolutely impossible to transfer the power to asphalt. On the street, cubes rule.

25THRSS, the mechanical limits of crankshaft loading, the physics of piston G-forces, etc, is not retarded. The stroke-vs-destroke argument has little point on the street, I will admit, but a fully built 383, using a cam which meshes perfectly with the mechanical limits of the 383's maximum rpm, will produce *slightly* more torque at any given RPM than a 377 with the same cam, however, the 377 would be able to use a *slightly* more radical cam and still hold together mechanically, thus via moving that *slightly* lower torque curve higher into the RPM range, create *slightly* more horsepower. The word of the day is slightly, the difference between a 3.48" stroke and 3.75" stroke is not radical enough to be awfully meaningful to 99% of people. The added cubes of stroking rather than destroking the 400 are far more meaningful on the street.

I note again, the destroke argument was not intended as advice, merely as explination of theory.

 

.

 

As I said, even with a 383, it can be built to the point of being unable to plant the torque. There comes a point when what engine doesn't matter, but instead how it's tuned. If you want more power, go for more cubes. For a small block, the 427 would be ideal.. for about 8 grand. Even the 400 would be great.. good luck finding one. The 383 is the cheapest of the small blocks with greater potential than the 350. The 350 blocks are plentiful and the 383 rotating assemblies are only about 900-1200 bucks.. big block swaps I know nothing about. I've got small blocks on the brain.

If funds are unlimited, I highly reccomend the small block 427 vs big block 427 or 454.. I don't think the 27 extra cubes of a 454 is worth the added weight of a big block. Bang for the buck, though, the 454 should be about 1/10 the cost of the small block 427

 

.

 

Because the SBC 427 is not a production motor, aftermarket only. I already said this once, at the top of my second to last post. They cost about 8 grand.

 

Here is a big block conversion you can check out.Big Block Swap

Steve

 

I did a 383 swap with TBI and it didnt go well at all. I had to go to carb to get it working correctly and cut down on the risk of a heart attack or stroke from all the stress I was experiencing trying to make it work. I would suggest buying a crate motor already dyno tested to make things more smooth. If I was gonna do it again, that is what i would do.

 

I don't think people understand that higher rpm DOES NOT equal more hp. I would much rather have a 550-600 hp 406 that makes good power up to 5500-6000 than a 350-400 hp 302 that can pull to 8,000 rpm. Hp comes from tq so anytime you increase tq you must have more hp and vice versa. Cubic inches is king any way you look at it. The only reason destroking came about was to meet certain cubic inch requirements in a particular racing class. I completely understand everything you are saying smurf, but all that said, more cubes, in the form of stroke or bore is still more power. Like I said, purposely destroking an engine when you don't have to in the interest of power is stupid. Lets say I was in a class with a displacement limit of 400 small block cubic inches. Do you honestly think anyone who wants to win would run a 377? Hell no, they'd all go for the 400 block.

 

I'd have to agree. All horsepower really is is a calculation, it's torque that makes your car move. Having more tq than hp means it takes more effort to get the vehicle in motion (better acceleration at higher RPM's), and having more tq then HP means it takes less effort to put the vehicle in motion (better acceleration at lower RPM's). Having a high # of both is obviously a good thing, giving you an even power band, and the bigger the block the better the potential for both. The ONLY thing destroking a motor will do for you is skew the power band, especcialy with that large of a block. The potential a 400 block has is rather significant, and keeping that even powerband is not only smart, but not stupid! (for lack of better wording ) Like 25THRSS said, destroking is PURELY for regulation reasons. Kinda like restrictor plates, I guess...

Bruce (90RS305)

 

.

 

No, I understand that quite well... in a perfect world, we'd have more bores to play with and we'd be able to get 406ci motors out of the 302's crank.. then the mechanical limitations would become very obvious, and we'd be talking about a 1200+ horsepower @12k 406 that couldn't pull from a traffic light to save its *** from a semi hitting it without burning the clutch to hell or using a 4000+ rpm stall converter. It doesn't belong on the street anyway, and I tried to make this abundantly clear.

And yes, I conceed that if there was a small block with a bore to get 406 cubes out of a 3" crank, everyone and their monkey's uncle would put a 4" crank in it and grin like idiots with their 541CI small block, including myself.

I don't think people understand that I was merely explaining the concept for theoretical purposes. As such, this thread is just becoming too much of a headache for me. I'm done. Everyone, believe what you want.

 

I've seen a 454 BBC in a thirdgen before. Don't know if the firewall was pushed back, but the guy got it in there. The main reason people go with the 350 over the 400 is definetly cost, but also driveability. I'm sticking with my LO3 in my car, if I go with a bigger engine it'll be in a different car, cuz I like getting 20mpg in the city. There are other reasons too, but those stick out the most...

 

.

 

The real question is what do you really want to get out of it? Are you going for an all-out 1/4 mile car? Or do you want something comfortable enough to use as a daily driver? Every engine/tranny/gear combo has its pluses and minuses. A 400 with 4.10's in the rear will get you to the end of the 1/4 faster than most people can say 'Super-Cala-Fragalistic-Expy-Ala-Doshious' (like 4-5 times) and like say my 305 with 2.73's can break into 15's, but still gets 20-30mpg. As you've more than likely seen here on TGO, engine combos is one of the biggest and most heated debate topics in the forums...

 

.

 

.

 

If money is no object, I would buy a Moser 12bolt, Probuilt 700r4, Bill Mitchell 454sb(world products) and all the spohn thirdgen suspension parts and subframe connectors. Don't forget the Holley 900cfm tbi and Comander 950 ecu(I personally would go with a Stealth Ram)to run it with. That should only set you back about 18 grand. I'd say you would have one mean Camaro.

Steve

 

I'd say!