How would this work::

406 with around 9:1 cr

mild hyd roller cam - say 215 to 220 int and 225 to 230 ex with around 500 lift and 112 to 114 LS angle

Unported decent casting stock heads with 2.02"/1.60" valves

Stock TPI unit with stock 350 (22 lb?) injectors. Fuel Pressure turned up around 46 to 48 psi. to feed the extra cubes. And an aftermarket chip.

Would this make a torque monster that would run outta breath at 4000 rpm but really pull hard til then? Just how many cubic inches can the stock TPI feed reasonably? I've heard Chevy designed it for only 305.

 

can u put the stock TPI on a 406.. SURE.. go for it.. is that 406 going to be able to breathe or have any power.. HHEELLL NO!!! u need to port the intake, plenum, and get a 58mm T.B. and atleast some 26# injectors...

as far as the 4000 rpm range.. my 406 power band starts..well tq wise.. at 2100'ish RPMs.. and pulls all the way to 6300-6400. at 4000 rpms u havent even begun to reach the HP it can make. and as far as ur heads.. do urself a favor.. put some 2.02 1.65's or 2.05 1.65 on them.. these engines need to be able to breathe.. so u putting stock heads, and a stock tpi*which was really only made for a 305* on a 406.. u just waisted ur money on that engine.

**edit**

currently i have 26# injectors at 59-61 psi on my 406 tpi.. 26# injectors at 45 psi is normally enoguh to feed it, but for some reason mine wants more fuel *last dyno run i was around 20 inthe a/f ration at idle.. but the sec they hit the gas my a/f ration went to 9-10. so now im going to get some 30# SVO and put them around 45.. which may be bit of an over kill. *i i think 28s would be fine.. but id rather have the 30's 4 when i put a s/c on it*

 

Thanks for the reply. I understand what you are saying about better heads/aftermarket (or ported) TPI being more suitable for an engine this size. Even for a stock 350 those mods work best- but, what I'm asking is will going to 406 cid with the stock TPI produce a strong street engine of the next step up in size similar to what the factory got when giong from 305 to 350 cid. In other words, would it result in a few more HP (20 to 30 maybe) and more TQ (25 to 50' lb) than a stock 240 HP / 345 TQ L98 motor ?? I know it wouldn't be anywhere close to your aprroximate 400 HP/430 TQ, but is 270 HP/395 TQ or so a good estimate/goal? Also, where would it run out of rpm on an engine this size in stock form? I'm guessing about 500 rpm lower than the 350. Surely someone has built a 383 or 400 and installed their stock runners, plenum, intake, & TB on it.

 

It will work but your wasting the potential of a 400 by only aiming for 270. Hell a good running 305 can get you 270hp. I just installed a Superram on my basically stock 350 and the difference is unbelievable and this is without even any tuning. The stock tpi intake will make power up to about 4k but its a battle to go any higher and I even think an SR and baseplate makes more tq and hp throughout all the rpm range, not just over 4k. If anything, spend 400 bucks and get an lt1 intake which will feed the 400 much more adequately.

 

YES I HAVE A STOCK TPI ON A 406 USING 24LB SVO INJECTORS AT STOCK GM PRESSURE AND A STOCK CHIP (FOR NOW). I AM USING A MAX OF 4500 RPM. JUST DEPENDS WHAT YOU WANT. AT 60MPH IN OD, DO YOU SHIFT INTO THIRD AND GET 3000 RPM, OR INTO SECOND AND GET 4500 RPM. AND AROUND TOWN YOU RUN AT 2000 RPM, SO YOU HAVE PLENTY OF PUNCH WITHOUT HAVING TO SHIFT DOWN AND WIND IT UP. COME AROUND A CORNER AND HIT THE GAS AT 1500 RPM IN SECOND, AND THOSE 255/50R16'S START TO TURN OVER. IS IT FASTER THAN AN L98 ?? YES IN MY CASE. WIFE HAS A 90 IROC-Z WITH L98 ROLLER CAM. MINE IS 86 TA 406 WITH HYDRAULIC CAM. I GET OFF THE FREEWAY, TURN LEFT AND GO TO THE OVERPASS. IROC SHIFTS AT 5500 AND DOES 60 MPH TO THE BRIDGE. TRANS-AM SHIFTS AT 4500 AND DOES 66 TO BRIDGE (SPEEDO IS NOT CORRECTED FOR THE 255 TIRES ). IROC HAS 245'S ON REAR, BUT BOTH HAVE SAME GEAR, 3.27'S.

I DID CHANGE THE INTAKE. TOOK OFF THAT SMALL CANISTER AND THE TWISTY BOX AND INSTALLED A STRAIGHT 3 INCH PIECE OF TAIL PIPE. TAKING THE STOCK PAPER AIR FILER OUT OF THE CANISTER INTO THE OPEN MADE RUN RIGHT UP TO 4500. WITH THE CANISTER, IT LAID DOWN ABOVE 4000. I HAVE CHANGED THE PAPER ELEMENT TO A K&N, BUT HAVE NOTICED A LOT OF IMPROVEMENT OVER THE OPEN PAPER ELEMENT.

BY BUILDING A BIG TORQUE ENGINE, I WAS ABLE TO SAVE A LITTLE ON HEADS, INTAKE, AND I ALSO DID NOT CONVERT TO A ROLLER CAM. THOSE UPGRADES WOULD HAVE COST $2000 MORE. I AM HAPPY WITH THE RESULTS, AND MY MPH WENT UP TOO ( 305 GOT 18 HIWAY, AND 406 GETS 20+ ).

 

In short, It would work Great!!! And smoke mildly modded 350s!
If I were to guess 400+ Ft Lbs and 300+ HP! I say DO IT!
Most people are going to laugh at this set up I have put together and am currently running in my 85 Iroc until I Totally Build it up with Heads, SR, Headers, bigger cam, etc... I have an almost stock 305 TPI set up (ported base and a BBK AFPR with 305 injectors at 50 psi and an air foil) This is bolted to rebuilt std. bore 400 with a Summit Racing 214 in. 224 ex. cam. I am running (ported) 305 TPI 58cc heads and a 1.6 intake rocker to make up for the small intake valve, a couple other internal goodies and get this, STOCK exhaust manifolds!
This engine mated with the drivetrain I am currently using is EXTREMELY FAST, Considering!!! , It Idles like a dream, and right now is totally streetable and pulls extremely hard to 4000+ rpm. With using only tubular LCAs and 255 rear tires and a Strong Posi, this combination has gobbs of thrust, (Shift kitted 700R4, a TCI Sizzler conv. and a 3.23 posi). I only have about $1200.00 invested in upgrades on this whole Drivetrain which includes the cost of the 400 shortblock!!!
Im NOT bragging but I have most likely put together more engine combinations (305s, 350s, 400s and put them in these F bodys than most people on this board). Making these smaller engines perform can get very expensive!
It kind of bothers me whenever most people respond to this topic because they always put down the idea or respond like money is NO OBJECT, I think the people asking about this swap are aware that the 400 or 406 will not breath to it fullest potential with the stock TPI but just want to get started with more cubic inches.
I would recomend to anyone to START upgrading your car with a 383, 400 or 406 and someday if they wanted to, upgrade everything else.
I have had in my above Iroc alone 3 complete different drivetrains. My set up before this was a 10.2 - 1 Trick flow headed 350 with all the goodies 216-228 Crane cam plus Accel runners, Edelbrock baseplate, 58 mm TB, 24lb. inj, Edelbrock headers, 5 Speed, 3.73 gears and the list goes on forever.
The point I am trying to make here is at one time I have had about $5000.00 into an engine & injection alone in this car and it WAS EXTREMELY FAST, But dollar for dollar in my opinion, upgrading to a 400 or 406 FIRST IS THE BEST starting place to increase the performance of a stock TPI F-body,(Rather than Runners, Heads, Headers etc) first on a smaller engine.
Just my Thoughts!!

 

I can relate to guys who have spent all that money building a 400 and now find they are tight on cash, so they scrimp and install a stock/ported TPI intake.

But, for $400 more they could install the LT1 intake and be SO MUCH FASTER. It is a "must have" in your build up budget and you should figure how to include it in the buildup.

I just swapped a Miniram with mildly ported L98 heads onto my otherwise bonestock L98 (including cam for now) and it is like a new engine. People that say I would lose bottom end torque were WRONG! In fact, the engine is stronger below 2,500 rpm and there is no comparison above 4,000 rpm. The only place it might be a little softer (and I mean very little) is between 3,000 - 3,750 rpm...and it is only noticeable because my engine is so much stronger everywhere else.

If a Minram (which the LT1 intake is virutally a clone of) made this much of a difference on a basically stock L98, imagine what it will do with a 400.

After spending ALL that money, why do you want to slow yourself down? Dump the TPI and get an LT1 intake. You WON'T regret it.

 

Just make sure that your valve train is up to the task of increased RPMs. Glenn learned that the hard way

 

Just a collapsed lifter from the stiffer springs (for my future cam), no big deal. After 200,000 miles (300,000+ Kms) they have served me well. No one was REALLY sure if high mileage Hydraulic Roller Lifters needs to be replaced, so I decided to see if I could cut some corners since they aren't exactly cheap.

The Miniram makes it a lot easier to get at. I can have the intake off in less than an hour to get at the lifters. This is one of the principle reasons I chose the Miniram over other intakes (the LT1 should be similar for R&R unless GM fubared the design).

The problem is the little old ladies in the strat-council in my building held a meeting and voted to serve me notice that I cannot work on my car anymore. The joy of living in a strata building.

So I have to buy a house with "fee-simple" title now if I want to work on my car.

 

When you guys suggest a LT1 intake, do you mean the WHOLE fuel injection set up or JUST the LT1 intake instead of the factory TPI unit.

I think that going to the 400 block would be a great idea. I think that I will try that.

 

85TPI400,
That's exactly what I plan to do. I am getting a 400 but don't have the dough for the heads I want right now so I am using ported 305 heads with 194/1.60 valves. I have a ported Eldelbrock base and Slp's so they will help some. I am considering the LT1 intake swap after the motor is fully done. The Stealth Ram is looking good as well.

 

i thoght they stoped making 400's in 79, i guess the bolt pattern's are still the same on the tpi?

 

The TPI intake bolt pattern is the same as the 400's. On 87 & up TPI's with cast iron heads the 4 center intake bolt holes will have to be enlarged due to their odd angle as compared to 1955 to 1986 models & L98 aluminum headed corvette models.

 

i thoguht the pontiac 400's were BB's and chevy 400's were SB's... then agian... im sure im wrong

 

Actually Pontiac 400's are the same size externally as all other Pontiac V8's. 350 to 455 are all the same height, width, length, etc. Just bore & strokes are different.

Like 283 to 400 cid small block chevys are the same size.

This post is about using a small block chevy 400 engine.

I wouldn't put a pontiac motor in my car unless it was the ONLY thing I could get, and I wouldn't like it then.

 

What's wrong with poncho motors?
other then the fact that the aftermarket isn't really there.

 

There is nothing wrong with Pontiac motors. It is true that there is no such thing as a small block or big block Pontiac, they are all the same block. Having said that, I would rather use a Pontiac 400 over a chevy 400 any day. I have my reasons, I just like real Pontiac motors more than chevys, but since 3rd gens only came with small block chevys then that is what I will use.

If I could convert a Pontiac 400 to TPI, I would do it.
It just simply isn't cost effective to do so. The torque would be incredible!!

 

 

Hey thx for this post. I think I'll be buying that 400 sbc this week.

RP.

 

Just as a reference point...from someone else who put an almost stock TPI setup on my 406...

It worked fine...now the caveat is that I had a custom chip from Fastchips and used the stock TB, plenum and runners with an Edelbrock base (due to having stock 1970 heads)

The HP was limited (obviously) but it was way stronger than the stock 350...that is for sure...and the drivability was great.

I would ALWAYS ALWAYS ALWAYS go with more cubes first and do the other mods when money permits...you will be happier in the long run...

Good luck.

 

You just need the LT1 intake and fuel rails. Add a remote t-stat and custom fuel lines and you're set.
You re-use all the old wiring, throttle body, injectors, ect....