David#49roced-u

Ok I have both a 400 small block and a 305 tuned port and was wondering if combining the the 2 would be a good idea. I have heard that from a guy that a 400 goes well with the tuned port but I still have my doubts. Anyone got some experience or input?

InfernalVortex

iTrader: (4)

TPI chokes a 305. It's a compromise in a lot of ways, and the smaller the displacement the better the compromise works. TPI chokes a 350, it chokes a 383 even more, it'll choke a 400 more than that.

Will it work? If you get it all together and tune it, absolutely. But you'll leave a lot of power on the table. You'll need to keep a small cam to match the TPI's power curve or you'll have a car that's sluggish down low and dies up top too. Either way you can get a lot of power from 400 cubic inches, but you're not gonna get all of it with a TPI system.

formula1LE

iTrader: (3)

Ehhh... not too sure about that. I plan on building a 377/w Fast Burn heads using a TPI with a StealthRam, LS1 injectors,and an LS1 interface that will run the whole TPI setup. With tuning, 500 HP should be easy to accomplish...but then again, a ProCharger is soon to find it's way on the engine soon after the initial tune.

Stephen

iTrader: (12)

Bad combination. It CAN work, but not real efficient or as good as it could.

TPI excels in low RPM torque production. 400s excel in high RPM horsepower production. The TPI will run out of air, before the 400 can really start working.

383 + TPI works real well. Both are torque monster recipes. Combine them & you can easily make over 500 ft lbs without breaking a sweat.

Blazzin87

sounds sexy

IROC-You

a 400 TPI motor will be amazing... in a truck.

The 350TPI was the best truck motor ever made, the sad part is that GM never put it into a truck.

bowtie316

GM didn't put it into a truck, but I just did. I'll get some road time tonight to test out how well it works.

I agree that a 383 TPI would be a stump puller to around 5000 rpm, I think the 400 will have even more torque, but will drop off around 4500 rpm. For my lifted truck with oversize tires, I think the 383 or 400 TPI would be awesome. Afterall, we're only talking about 17 cubic inches difference.

InfernalVortex

iTrader: (4)

You'd make a lot more horsepower with a carb or aftermarket EFI system though. You'd have a lot more room to pick some bigger cams too, instead of dancing around the high RPM limitations of TPI.

Think about it like this. TPI runs out of breath around 4500 RPMs. You put it on a bigger motor and it's just gonna run out of breath sooner.

Even a small aftermarket cam like my 218/224 job has a power curve up to 5500 in a 350. If you put a that cam in a 400 TPI it would make a lot of torque, but itw ould only make power to around 4500, and the TPI only to about 4000 probably... so if you ever wanted to make some serious high RPM horsepower... you'll never get past the 4k RPM wall.

Understand that horsepower is (basically) torque x RPM. The more torque you make at high RPMs, the more horsepower you'll make. TPI cripples that ability to make high RPM torque.

You can pull stumps and tow field plows around all day long, but you're not gonna be able to compete with some guy that put the same 400 with a bigger cam and a carb on his car.

warriorcustoms

Im new here But Im wanting to build a 400 sbc with TPI and Vortec heads The funny thing that makes me laugh is the 383 coment A 400 sbc isnt a screamin high horsepower motor its a brute torque motor SO if you pick a cam to match the short comings of the TPI it should easily make more torque than a 355 or a 383 combo Mine will be going into my S series blazer when i do my solid axle swap GM Hi tech did a build on a 355 vortec that is sweet and the 400 should make 400+ hp and 500+ ft lbs of torque and get better gas milage than my stock 4.3 Heck Id be happy with just 500+ ft lbs and 375hp like the 355 build LoL I found a complete TPI for 100 bucks off a 89 vette Bet thatll be mean in any street machine YOU dont have to scream stuff to the moon if you have enuff cubic inches NO REPLACEMENT FOR DISPLACEMENT If the tpi doesnt suit me or anyone else You can always use the GMPP ram jet 350 intake they came on mercruiser boat motors too

warriorcustoms

Most people build a 383 because factory 400 blocks are scarce and aftermarket puts their budget way over Just my 2cents LoL

articwhiteZ

iTrader: (56)

just get a better TPI intake then the stock GM TPI.

and go from there.
lets take lingenfelters 420 sbc with a super ram thats over 550 hp in a street eng that passes smog, and over 400FPT at 1600RPM Go fig.

me i like Big small blocks, and EFI, i use what i know works.

warriorcustoms

Artic thats SWEET So is it the runners plenum or baseplate thats restrictive or all the above??? Been awhile since I studied TPI (high school 1990) Lmao Its always how fast ya wanna go = how much money ya wanna spend LoL Me personally Im past all the wild work on it every day race motor on the street So keep the revs at like 5500 redline and more cubes I could always go up to any of the big cube versions like 434 454 or 472 but 406 should put a **** eatin grin on anyones face My uncle raced a 406 on the dirt in indiana and it was a stock rebuild with a blue racer cam Lmao IT would smoke the 355 and 383s that had over 10grand in the build

Stephen

iTrader: (12)

You might wanna rethink that a bit.

Look at the bore vs stroke ratio. 383s excel at low rpm, just like the TPI excels at low rpm. 400s are just the opposite. They prefer high rpm. Mismatch for TPI.

Will it work? Sure! Will it b e as good as it can be? No. Get some high flow TPI runners, like the siamesed ones, THEN that 400 will be much happier.

I'm not saying a TPI won't work or won't produce good numbers. But for 400hp & 500+ft lbs torque.....STOCK TPI plenum & runners can do that pretty easily on a 383. I've seen it done.

dhirocz

iTrader: (2)

There is nothing wrong with a tuned port 400 small block. All the junk you hear about 'choking' is hocus pocus. Why? Because that is the only way a TPI engine can work. If a tuned port wasn't choked, it wouldn't be tuned.

The 'choking' speeds up the air velocity which when combined with runner length provides the tuning effect at a certain RPM. Therefore, a more productive approach would be to make the engine more efficient while not sacrificing velocity (IOW cross sectional area)

I would prefer a 383. Why? Because stroke, the scavenging effect on the exhaust, camshaft and the intake dictate most of how and when torque comes in on a TPI engine. The extra few cubes will lower the RPM range. 383's have the same stroke but a slightly lower airflow requirement than a 400 or 406.

The biggest problem people don't fix on larger tuned ports is matching the length and cross section to the same RPM via porting. Runner length for the most part is fixed, and that combined with your cubic inches should be your torque peak target. With that you port your intake to match and it would be a perfectly fine, well running engine. You can only adjust the runner length with runners like SLP's.

Putting a stock TPI on a larger small block would be mismatching the runner length and cross section, so it wouldn't work as well as it could.

The 305 TPI was tuned for a 4000 RPM torque peak. Even though it's mismatched, you can see why the camshafts are so small in 305 TPI's...it lowers the peak. You dont think GM wanted a 305 TPI walking all over a 350 TPI do you? This is why there are some 305 TPI's with factory intakes outrunning 350's; the lower airflow requirement and same stroke as a 350 allows a higher torque peak RPM than a 350, allowing a higher HP RPM. This is why I chose a 383 over the 400 or 406...

...longest stroke and smallest ci engine without bore shrouding is the best approach.

articwhiteZ

iTrader: (56)

you can have all the 383's you like, i have LINGENFELTERS, stage 5 383, and will be Kicking it's *** with My new 427 and the same intake.

that was on My 383,

383s, ya i remember when it was fun to Have one, but true Power is to be Had with More Cubes, thats the way I roll!

and who knows in 3 or 4 more years the new 440 will Be taking over for the 427.

Stephen

iTrader: (12)

440.....Yawn. There are already 454 SBCs out & I'm not referring to LSX engines. Have been for years. Besides, 440 is so "Mopar" I doubt they'll try to build a Chevy 440.

BTW.....Is a ling*I*nfelter a knock off ling*E*nfelter? Just bustin' your ***** there!

articwhiteZ

iTrader: (56)

OOPS Lingenfelter.

yes the 454 sbc was and is the same price to do has my new 427.
just going up in Bore is all. still a 4" stroke. and more Tq then a 383

and yes you can get it in the ball park of 440 cid

383s are like 350s now, every Body, and there Dog, has one.
heck even GM sells them..and i even had one in my new 92 Z28 back in 93.

But today you have to think Bigger, chicks Dig Bigger CIDs (spelling)lol

warriorcustoms

We ran and built over 20 small block 400 combos on the short tracks of indiana and you don't have to scream a 400 LoL you contradict yourself pretty bad A 400 might like more air but not RPMs I know what works and how YES you can scream anything if you want BUT why if you don't have too The biggest 400 based motor is 472 cu in most people I know have built 434s not 440s LoL .060 over bore usually over heats like a bitch unless its filled and just for the drag strip The 400 siamese bore on a street motor .040 is MAX You might wanna go back to your RE THINK on the 400 Lmao One of the magazines done a 406 build on a 406 TPI 15yrs ago and it was mild and made 550ft lbs of torque without vortec heads LoL

Stephen

iTrader: (12)

Got a link to it online or know which issue? I might have the magazine & would love to check it out to see what they did.

warriorcustoms

Im kicken myself in the *** for gettin rid of my 3ft stack of magazines If I remember right it was a vette rag or maybe super chevy I reasearched hard when i was in high school because i wanted a TPI 400 in an IROC back then LoL If I can find a Ram Jet set up Ill do that But for 100 bucks the 89vette set up will work just fine Its got HiFlow runners already & with the vortec base from Scoggin Dickey The 400 will be a mud slingin SOB in my blazer the tacs redline is 5200 so an interface for it and the vortec 400 with a little cam will match everything LoL Ill see if i can google the build from back in the day Heck it might of been Tuned Port Injection Specialties (TPIs) I did have their one catalog They even had a 406 TPI in a JEEP

Apeiron

I could see that... and that torque peak was probably at 2000 RPM, and the HP would have peaked at about 250 HP @ 3000 RPM.

warriorcustoms

they kept everything below 5000rpm Check out the GM Hi Tech 355 TPI build its sweet and everything the same on a 400 short block would make it down lower to make it at the same peak you would need about 10 degrees more duration on the 400 I want it down low Turnin motor to 8grand on the street aint fun after awhile Hell if I talk this other old dude out of 1 of the 3 69 camaros in the barn Ill put it in that MAYBE LoL An LSX mite go there in a big inch combo The ole dude Im gettin the 400 off of wont sell **** to anybody But 2 days of shootin the breeze Its mine LoL 6hrs of talkin chevys paid off

warriorcustoms

If it helps Daves decision any the TPI set up the stock tuned port set up will support 420hp if you need more look into the ram jet , TPI500 , mini ram, or the super ram should I keep goin LoL

Stephen

iTrader: (12)

Except that those examples are all short tube runners. It it the long, "thin" tube of the OEM runners, that are the biggest hurdle for a TRUE TPI to build higher RPM horssepower. The OEM TPI runners simply cannot feed the needed air at higher RPMs.

Those examples are closer to LT1, which can produce higher hp but lower torque, for the same combination underneath it.

warriorcustoms

Yall crack me the f**k up SO i guess all the companies that specialize in TPI stuff are full of s**t TOO Yall mite wanna research and talk to a few tech departments at more than one of em then

articwhiteZ

iTrader: (56)

I dont use 400 blocks, i dont have any heat probs with any of the Engs I have Done.theres a bit more to it then just Bore..lol

i use aftermarket blocks to make Cubes, and a 4" stroke has Nothing to do with a 400cid GM Block. you can go as much has 4.250 bore on some aftermarket blocks, with out any probs.

and making 600 Hp under 6500 RPM is Not Hard with the right parts.
and a short track eng, would not be the same Eng power ball park as a good 12.1 427 with a 4.125 bore and a 4" stoke, somthing you would never get into a GM 400 block

how fast you want to go = how much money you spend, thats the bottom line.

but i's all about Fun with your Hot rod.
most guys would not use 12.1 on the street, I see nothing wrong with it, we all know it's going to need good gas, the thing is if you want the power, then use the parts you need to make it, dont skimp, it's no fun to skimp.

nothing like 400 PFT at 1600rpm and 550 FPT at 6000RPM

with Tq like that. you have a fun car. use the right intake to Feed it!

dhirocz

iTrader: (2)

Not true. I've built many 427-440 ci SBC's, based on factory blocks. The biggest hurdle is cylinder wall thickness on the thrust side, and you need clearanced rods, notch the block, and run a small base circle cam. It is POSSIBLE to fit a 4.125" stroke, but it's not worth it and very difficult even with the right parts. The deck height is also too short to maintain a decent rod length to stroke ratio.

Just for the record, the only time a 400 or 406 ci TPI is a better idea than a 383 is if it's financially a better deal OR if the heads flowed too much for the 383 to possibly use (which is hard if the TPI intake is ported and sized appropriately) which would slow down intake velocity (which is more often a problem with HP builds). Of course, you can't complain with the deshrouding that comes with the extra size. Anyway, this is the reason high dollar TPI 350 builds aren't a good idea...the TPI engine just doesn't need a 280 cfm head.

articwhiteZ

iTrader: (56)

to much to go wrong with a standard 400 Block, to many games to play, thats why they make aftermarket blocks,
spLayed caps, thicker walls, bigger bores, just more HP, you can do anything you like.

all i can say is, I use aftermarket blocks, IV never had anything i had to worry about, Like cutting into water Jackets when notching a GM 400 Block, or using filler to fill up the bottom half of the block so it dont leak,
or thin walls, using a GM 400 to do a poor mans stroker might be fun, but you will have core shift with thin walls, and other things iv never had to worry about, iv used Dart / GMPP / Wheeler, to name a few. ill stick with a Bomb proof bottom end. with lots of meat, to take all the NOS i want to use,

after all dont skimp and you will have a eng that will hold up more then just a few weeks.

the big inch small blocks are for Maken TQ! you can use a good aftermarket intake and Get Good #s with EFI

1991z285speed

I am doing the same thing as the guy who started this forum.

305 TPI to 400 TPI
Questions:

Would my 305 heads work well with the 400 + TPI set up? If not what will bolt up to my tpi system and which heads?
Would I need to buy the high flow manifold along with the high flow runners to help it breath better?
Please critique as much as possible. I found a really good 400 sbc short block and a seasoned mechanic willing to help me out.

My goals in this build are to:
1. Learn how to build and rebuild a motor
2. Do so at a budget and get rid of the damn 305
3. Gain some hp and torque.

drefi

No

Banedt

400's make huge TQ....but run outta steam just past 4500-5500rpm. With a nice mild cam, roller would be best, a TPI 406, will smoke a 383 in the TQ department. Go with bout 70-72cc heads, 18-22 dish piston. No 383 ever built can match TQ a 406 can make with the same engine parts. HP maybe....TQ NEVER! THERE IS NO CHANCE! Get a head that flows bout 195. I'm betin 450 hp 525 tq. An never get over 4500 rpm

TTOP350

iTrader: (8)

My 400 stroker has a solid roller cam, afr 245 heads, mini ram and she pulls to 8k.
Yup, low rpm stump puller here.
A 383 and 400 have the same stroke, 3.75. I dont understand the 383 thing much really. You can make a 350 block a 401 or so with only a couple hundered bux more. The problem with the 383 is most people use waay 2 small of a head and cam with them.
I use 400 2bolt blocks and add splayed caps. It took 4 blocks to find a "good" one. I will do a aftermarket block nex time for waaay more cubes. The only reason I used the factory block is because I wanted to push it to see what she can handle.

Guys, you can make any motor work in any rpm range you want.
Its all in getting the intake, heads, exhaust and cam for the job your wanting it to do.
Get your budget figured out, a power plan that will work in the budget and then you can build your motor.
Cheers an Beers..

383Rocket

For what its worth years ago SuperChevy magazine showed a glimpse of a TPI 400SBC that Arizona Speed and Marine did up, thought the TPI intake was reworked it was a stock unit, and it made 500FT-LB of torque before 3000 RPMs. But it was built using marine components, and I think it was put in a road race car. Anyways, a 408 with 6 inch rods, and a modified TPI system would probably be great for a truck.