[455TA]

Here is a complete setup of my engine currently.
455, .030 TRW forged pistons, stock rods with ARP bolts, Factory N Crank, Factory caps and bolts. Compression comes in at 9.57:1.
Edelbrock heads - flow 307 cfm, 2.11/1.77's, round ports, 89cc.
Butler Performance metal head gaskets with copper coating. ARP Bolts.
xr288hr-10 Comp Hydraulic Roller - Specs are 236/242@.050 with 600/620 lift with the Harland Sharp 1.65 Rockers, 110 LSA. Spring pressure is 160 lbs on the seat.
Multiple intake manifolds to use - all port matched. Torker II, RPM, and Northwind - Would lean towards NW for this setup.
FiTech EFI - 1200 HP capability. Has 8x80 lb injectors. Fuel pressure set at 58 psi. Using a Tanks Inc fuel tank, Walbro 400 lph fuel pump, and -8AN feed lines, -6 Return. Aeromotive Fuel Pressure Reg.

Th400 Trans, 10 inch UCC torque converter - stalls at 3400 rpm and is relatively tight.
New driveshaft being built currently with 1350 joints.
10 bolt rear, Strange Chromoly yoke, 3.42 gears, Moser axles, braced cover, arp carrier studs, 1/2 inch wheel studs.

I'm wanting to turbo this thing. The car runs 7.15@95 mph currently in the 1/8th mile. Full steel body, full interior, etc. Roughly 3800 lbs.

If I were to get the headers built - already got them priced out, get an s480 Turbo, and figure out a way to intercool it, would it be able to live with 8-10 lbs of boost until I can get another shortblock built to handle more abuse?
It is a mostly street car but I love to take it to the track.
Any input is appreciated - and yes I know....Stock Rods

[GTOGEORGE]

Originally Posted by 455TA

Here is a complete setup of my engine currently.
455, .030 TRW forged pistons, stock rods with ARP bolts, Factory N Crank, Factory caps and bolts. Compression comes in at 9.57:1.
Edelbrock heads - flow 307 cfm, 2.11/1.77's, round ports, 89cc.
Butler Performance metal head gaskets with copper coating. ARP Bolts.
xr288hr-10 Comp Hydraulic Roller - Specs are 236/242@.050 with 600/620 lift with the Harland Sharp 1.65 Rockers, 110 LSA. Spring pressure is 160 lbs on the seat.
Multiple intake manifolds to use - all port matched. Torker II, RPM, and Northwind - Would lean towards NW for this setup.
FiTech EFI - 1200 HP capability. Has 8x80 lb injectors. Fuel pressure set at 58 psi. Using a Tanks Inc fuel tank, Walbro 400 lph fuel pump, and -8AN feed lines, -6 Return. Aeromotive Fuel Pressure Reg.

Th400 Trans, 10 inch UCC torque converter - stalls at 3400 rpm and is relatively tight.
New driveshaft being built currently with 1350 joints.
10 bolt rear, Strange Chromoly yoke, 3.42 gears, Moser axles, braced cover, arp carrier studs, 1/2 inch wheel studs.

I'm wanting to turbo this thing. The car runs 7.15@95 mph currently in the 1/8th mile. Full steel body, full interior, etc. Roughly 3800 lbs.

If I were to get the headers built - already got them priced out, get an s480 Turbo, and figure out a way to intercool it, would it be able to live with 8-10 lbs of boost until I can get another shortblock built to handle more abuse?
It is a mostly street car but I love to take it to the track.
Any input is appreciated - and yes I know....Stock Rods

I think you answer your own question!


GTP George

[JLMounce]

The stock rods are the mystery and the main reason I haven't gone this route already. I have a similar engine combo with the TRW slugs and stock rods.

There's a lot of information about how the factory rods start to fail as you impart more RPM into them. There's surprisingly little information that I've been able to find in regards to how much power they will handle in the rpm range they were designed for. Pretty much everyone just says "they are strong when kept to their rpm limit," which includes Jim Hand's books. Very little in the way of specifics.

Corky Bell's Maximum boost can't be specific to every engine, but in the engineering sections he discusses loads on connecting rods under moderate levels of boost. He seems to claim that the amount of stress created would typically be in tolerance for most factory rods assuming you let the turbo do the work for you instead of increasing rpm.

I go back to how would you build the engine to start with if you knew you were going to turbocharge it? You'd never even look at a set of factory rods for it. That changes when you've already got an engine built and are looking at a 4000+ price tag, just because you need a different set of rods.

In my case, I have an engine that I didn't originally build, so I didn't have the choice in the matter, but upon tear down of the top end and inspection available at that time, is in excellent shape. It sucks to think about building the engine again and further thinning it's bores, just to replace the rods. At the same time though, it would suck to have to source a new block and do the build again from scratch if the factory rods weren't up to the challenge.

And so lies the problem and why every time this type of thing comes up, you're basically going to get the same answer. No, it's not possible. Probably the truest answer is that they may last 100,000 miles of abuse on 8 psi just as easily as they may last one pull on the on-ramp before they decide to window your block. I haven't yet worked up the courage to be that guinea pig.

[GTOGEORGE]

In short, the smartest thing to do is get better rods.


GTO George

[JSPONT]

Yes, change the rods and use ARP bolts. I run the NW w/ a S475.
I have eagle rods for 5 years now, no issue. 8-10 psi will get you 700-850 h.p. depending on cam choice.
USE A GOOD HEAD GASKET TOO! I use cometics and have had no issues.

[charlie66]

Change the rods, THERE OVER 50 YEARS OLD!

[4RSFEDGTO]

I agree with changing the rods. That being said I had a 455 with a stock crank, trw pistons, stock rods with arp bolts, arp main studs, arp head studs, butler head gaskets, the same cam you have and ported 6x heads and made 597hp and 603 ftlbs at the wheels on pump gas and 10 psi with a Vortech YSi and CSU carb so it can be done. I may have been one of the lucky ones though. Car weighed 3650lbs with me in it and ran 10.39 @ 135 with a slow 1.48 60 foot..

[455TA]

I have a 481988 casting 400 block on the engine stand now, that is completely torn down and only had a few thousand miles on it since the rebuild in the late 80's. It is .030 over currently and may be fine going .035 over.
I definitely would like to build it to handle the turbo, but I guess I was hoping to stall that for a while and just slap a turbo on the current engine to get me by for a while relatively cheaply.
Thanks for the replies everyone! I guess it will be quite some time before I can do the turbo route because I'm a tight wad when it comes to spending large amounts of money at once.

[Tom Vaught]

Build the best engine you can for durability, as 8-10 psi of boost will last about one year of driving, (if you are very careful that first year like Charlie66 was).

Then the Boost Fever will kick in. Then the maint on the engine and parts changes will go up quickly.
15 psi is good, 20 psi is better, etc with a turbo. Your turbo selection should make 20+ psi easily with a 400 engine.
Charlie66 ran high 30 psi boost pressures before he calmed down a bit, LOL!

Tom V.

[455TA]

Originally Posted by Tom Vaught

Build the best engine you can for durability, as 8-10 psi of boost will last about one year of driving, (if you are very careful that first year like Charlie66 was).

Then the Boost Fever will kick in. Then the maint on the engine and parts changes will go up quickly.
15 psi is good, 20 psi is better, etc with a turbo. Your turbo selection should make 20+ psi easily with a 400 engine.
Charlie66 ran high 30 psi boost pressures before he calmed down a bit, LOL!

Tom V.

Would it be worth the hassle of getting Billet main caps for the 400 with splayed outer bolts? Or just sticking with the factory caps and bolts? I go back to the project double down and see they used factory caps and made well over 800 HP and TQ with a Vortech, which puts more stress on the crank than a turbo will. My goal will be to keep the rpm's low and just let the turbo do the work. I think I would be happy with 12-15 PSI max once it's all said and done.
If I use the 400 block, I will go with a 4" stroke crank just to increase torque for when it's not building boost cruising, and leaving on the footbrake.

[GTOGEORGE]

Aftermarket block, I wouldn’t waste money on upgrading an old used factory block!

GTO George

[charlie66]

Forged rods and pistons are a must . A good cast crank with a good balancing will carry you if you keep it at 15 psi max. After that you're starting to step the line with durability and should go forged with that too . 2 bolt mains are ok too IF you use ARP studs with them. But 4 bolt caps would be on my list for the build though .

[Tom Vaught]

The actual differences are: (Dollars spent at the end of the day)
a) between doing all of the machine work correctly on the 400 block,
b) Having a new block vs the old 400 block,
c) finding a competent Machinist to do the work, etc

Just makes buying a new aftermarket "Bob and Frank" IA-2 Block (that already has the splayed main caps installed, etc), and the ability to easily get a 455 displacement (with your 4.0" crankshaft) with the larger bore size capability, a no brainer.

Just need to spend a bit more cash. The iron aftermarket block will be a bit heavier though.

I have owned 3 previous "Bob and Frank" Iron Blocks and was very happy with the quality of the blocks. I currently own a fourth iron IA-2 block (short deck) and an Aluminum IA-2 regular deck height block.

"Bob and Frank" are very easy to work with, as are the Butlers.

Forget the old Pontiac iron block, just spend the money on a new aftermarket block.
At the end of the day, you will be much happier.

Tom V.

ps IF you SWORE to NEVER go above 15 psi or 6000 rpm then I would say no worries on the Pontiac 400 2-bolt main type block with studs.
Luhn Performance has cap walk on the 455 engine (with studs) that made 863 HP and 900+ lbs/ft of torque. This was at 13.5 psi of boost.

[krisr]

Originally Posted by Tom Vaught

IF you SWORE to NEVER go above 15 psi or 6000 rpm then I would say no worries on the Pontiac 400 2-bolt main type block with studs.

This is a good tidbit of information to know. With a half filled block with Hardblok, I assume there would be a bit more tolerance/window with the boost and/or RPM?

[Tom Vaught]

Problem with the Pontiac Blocks is not the wall thickness or the need for a half-filled hardblock deal, The boost is only raising the cylinder pressure by about 10 to 15% vs a NA engine. The Boosted Block pushed on the piston for a much LONGER period of time vs each combustion event. Therefore a lot more torque at the same rpm points.

That Torque translates to the compression of the rods, load on the crank throws, and force downward on the maincaps. All of this is trying to make the main caps move.
And they DO MOVE. This is called "Main Cap to Block FRETTING" the caps are dnacing all over the place.

Splayed Caps, Thicker Caps, Taller Caps, Talled Alignment Dowels, all help keep the Caps from moving.

In the old days some engine builders used main cap assemblies amde up in a tied together main web to try to make the caps stronger. New Ford Blocks tie into the caps as do Hemi Blocks. They do this for a REASON.

The IA-2 blocks and KRE Blocks have all of this covered at much higher HP levels vs stock.

Tom V.

[krisr]

Awesome information Tom, thanks!

[455TA]

Definitely some good information. I appreciate all the feedback!
I'd love to have an aftermarket block, because I feel like it would almost be limitless to what I could throw at it, being mostly a street car and all. Now I just need to win the lottery

[GTOGEORGE]

It’s just amazing sometimes how people have the money to make the power but not for the safety side.



GTO George

[JSPONT]

I have had my boosted stock block for a long time no issues. I have not gone over 15 PSI. No need to on the street, I have trouble hooking 8-10 psi.

I do have a forged crank, and the center billet caps. Not splayed. I do not have the block filled I put a lot of street miles on it.
I had trouble with motor mounts, I had a chain holding it for a while but felt that was not the best solution. This past year I added a mid plate, hold the motor rock steady.
The arp bolts and billet main caps really helped with cap walk. When I first boosted my car is was a 10 to 1 455. When I finally blew the headgasket and pulled it apart, it had cap walk. That was a stock motor with arp bolts.
I have never had an issue after I put the forged crank , rods in.
My car is a tug boat too!

[455TA]

Originally Posted by JSPONT

I have had my boosted stock block for a long time no issues. I have not gone over 15 PSI. No need to on the street, I have trouble hooking 8-10 psi.

I do have a forged crank, and the center billet caps. Not splayed. I do not have the block filled I put a lot of street miles on it.
I had trouble with motor mounts, I had a chain holding it for a while but felt that was not the best solution. This past year I added a mid plate, hold the motor rock steady.
The arp bolts and billet main caps really helped with cap walk. When I first boosted my car is was a 10 to 1 455. When I finally blew the headgasket and pulled it apart, it had cap walk. That was a stock motor with arp bolts.
I have never had an issue after I put the forged crank , rods in.
My car is a tug boat too!

I've got a perfectly good 400 on the stand - I just find it hard to wrap my head around spending $8600 on a new aftermarket shortblock when I could probably build the 400 for half that and it still be reliable under 15 lbs.
I would go ahead and do the midplate before I put the engine in the car. Mine is around 3800 lbs roughly. But it's built well.
Tubular upper and lower control arms, Viking Coilovers. Calvert racing caltracs, good adjustable rear shocks. Subframe connectors, and aluminum body bushings. Gforce Crossmember. Only thing it lacks is a cage and a scattershield but it would get those along with the turbo setup.