Road Race Engine
 

Specifically 455 based. Can it be done and made durable?

The car would be a street car that also sees HPDE and possible time trials. So I'm not looking at anything incredibly exotic, but something that isn't going to puke it guts all over the track after a 20 minute high rpm session.

I've already got the 455 in the car, built by the previous owner, so I know very little about it.

XJ code 455, probably .030 over, #62's, P4B, Speed Pro Pistons. Outside of that I couldn't tell you what cam is in it, or what the bottom end components look like. I would assume it probably has forged rods, quality hardware and probably a stock crank.

I'd like to make around 500-550 hp with a powerband between 3000-6500. Moving the upper RPM limit up to 7000rpm would be ideal, but considering this is a hobby car and not something I'd be competing for every last .10th, not necessary. My main concern is having something that will survive the extended periods of high rpm use.

Can I retain the 455 I have and make necessary changes, or would I be better off going down to a block that has a 3" main?

To make the power I'm looking for, I'd be using a set of aluminum d ports, more than likely KRE.

I live in Colorado where we have significant altitude changes over short distances, so I'll be fueling with EFI of some sort. More than likely a Holley HP kit utilizing an Edelbrock Victor EFI (TII).

Thoughts? Advise?

Thanks in advance :)

Oil temps have been a problem with some people road racing with the 3.25 main. Oil containment is an even bigger problem with a stock pan, and even with the Canton pan, especially under hard braking.
HPDE and Time trials are short runs, usually 15-20 minutes. It might could handle the temps with a good oil cooler. I wouldn't run it anywhere near 7000 rpms though. More like 5800 until you know more about the cam and valve springs. I generally shift my solid flat tappet 400 at 6200, only occasionally take it to 6500. You can feel it fall off so no reason in the world to wind it up further.
I'm putting together a 7000 rpm 433, we had to put a lot of thought into the valvetrain for that, along with a splay capped 3" 400 block with forged everything.
Once you get the KRE's and new cam you might can move the RPM's up into the low 6000's.

Weight is also a big problem, I see a 69 Bird in your signature. With a steel flywheel, 11" clutch and quick time bellhousing the 455 will weigh in at over 650 lbs. Aluminum heads will help some, but the hood and front bumper assembly is well over 100 lbs if it's all steel.
You'll need some serious front springs and brakes with cooling for late braking if you want to compete in Time trials.
I've gone lightweight on everything and it's still nose dives under braking.

I'd take it out for some HPDE runs, keep it conservative, monitor everything and evaluate it after each session. Run an oil pressure light and gauge, by the time you notice a gauge it's too late. If you switch to a Canton pan they come with a bung for measuring oil temp.

Yeah I'd definitely be making some upgrades before taking it out for any events. I'm honestly not sure how the engine lives right now with the #62's on top. I've never had audible pinging and the engine doesn't run hot. I'm sure the altitude here in Colorado is helping it survive on 91 pump gas.

At any rate, I'd be looking at a minimum of a head and cam change (or at least finding out what cam is in it), along with a canton pan at the least. Right now it makes about 42psi at idle when cold and drops to about 38psi at idle warm on the oil side.

The plan does include a fiberglass hood to save some additional weight off the front end.

Those things I can sort, I'm more worried about a bottom end. If I need to, I don't really have a problem with taking the engine out and rebuilding it. But if a 3" main block is desirable for this type of situation, I might as well just continue to have fun with the engine in the car and piece together a new engine on the side.

Heck I could limit my sessions for a season or two while I do that and focus on tuning the chassis and suspension.

I have a extra 2 1/2" main 400 block available. Also a complete 2 1/2" main engine available.

Granted, I'm no expert, but I wasn't even aware of those blocks existed. I guess I better pull out Jim Hand's book again!

They don't "exist"...

If there are no rules on the motor having to be NA, I would build a something in the 389 to 406 cid range with 3" mains and plunck a Paxton type supercharger on it!

sorry, let me clarify, ....modified 400 blocks w/main spacers for a 2 1/2" main crank. The crank won't be in Jim Hands book either.:burnout:

"I'd like to make around 500-550 hp with a powerband between 3000-6500. Moving the upper RPM limit up to 7000rpm would be ideal, but considering this is a hobby car and not something I'd be competing for every last .10th, not necessary. My main concern is having something that will survive the extended periods of high rpm use."

That power level is relatively easy, but the rpm range is too high for the long stroke 455 to be reliable in long term use...IMHO

Those are great engines, but history has taught us that successful high rpm designs are based on oversquare designs, not big-long stroke engine with heavy internals.

The big 455 are, and always have been a bit hard on the bearings in high rpm/high HP use. Doesn't mean to shy away from one, with 3" main and lighter weight internals we've made great advances in that arena. Even so, building one specifically for sustained high rpm use just isn't a good idea, once again, IMHO......Cliff

3.25 main. I`d keep the rotating parts as light as possible with a moderate clearence on brgs. Keep the rpm`s lower than the competition and use the torque you will have, and they won`t ,in most cases. Use a taller gear and make that 455 muscle through the corners and have gears that will not need all the rpm`s in the straights.

In other words, use it like a Pontiac and not make it run in conditions like a SBC. They will last a long time IF you don`t rpm the piss out of it. Of course, oil containment and temp control.

Good information guys, this certainly helps! Looks like I need to try sourcing a 3" main 400 block if I want to keep a poncho in the car for this purpose.

Assuming I keep the rpm's down around 5800 and watch oiling, in your opinions is keeping the 455 in it now possible for a couple season?

Gearing right now is a 3.73 with a 27" tall tire so I max out at a bit shy of 120mph. Fr the majority of the courses here in Colorado, that's enough to not be up against the mechanical speed limit of the car. Save for PMI which has a half mile straight.

I wish the aftermarket blocks has a 2.75 main option.

I believe this scenario has been talked about some 50 years ago..... Smokey and Pontiac management having the big main/little main controversy back in the pontiac nascar days. Wonder who was right?

I've NEVER agreed on the 3.25" mains as an rpm, nor oil temp limiter.

Did PMD campaign 421s in the early 60's at sustained RPM on oval tracks?

Competing and being competitive are two different things, thought that needed to be pointed out. One costs way more than the other, that I don't think needs to be pointed out.

To have fun, use what you have, and take reasonable steps to make it live.

Good machine work, attention to detail on assembly, oiling (good pan), and cooling are key.

To be competitive, you would/should build an application-specific engine. Would think something like a 400 (3"), .060 over, long rod, light rotating component engine would be a good choice. And of course, along with all the proper support systems, dry sump would be best.

Oil cooler, PS cooler, differential cooler, good brakes and shocks go a long way in taking the extra steps.

If you look at the failures that occur in endurance racing, most of the time it's not core engine stuff that fails, it's support systems or other drivetrain items. Electrical is a biggie, believe it or not. Many run their' race engines past their' service life, and that's when you see actual engine failures.

I've beat my stuff before for more than 20 mins at a time, sometimes as long as an hour plus. I don't think it's as difficult as some may make out, common sense is a key ingredient.

ho428 - What are some of the common failures you've seen in circuit racing?

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Quality balancer.

I've never much been afraid of the 3.25" mains either. What hinders the basic Pontiac design is how heavy the crankshafts are, long strong, long/heavy rods, pistons, etc.

There are just so many far superior designs out there for sustained high rpm applications, a Pontiac 455 would be at the bottom of my list.

Not saying here it can't be done, but when it comes to high rpm's, and big displacement, it's just a LOT easier on everything when we have LESS stroke and more bore diameter to move the same amount of air if/when the engine sees sustained high rpm's to make any given amount of power.

There is a lot of "theory" involved with these things, especially when it comes to rod length for any give stroke. I don't get all caught up in that stuff, but do know that relatively heavy parts in the spinning/reciprocating part of the assembly, combined with long strokes, just isn't the best way to get this deal done.......Cliff

Or just do what you need to at a lower RPM.

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Also run a non-detergent oil for avoiding foaming issues.

I think with 3.25 main it might be a good compromise to drop down to a 4" stroke(440 ci with 4.185 bore)... Still good torque and less strain on the block... generally happier at rpm than 4.21 or longer stroke. Stock rod length is fine but BBC big end allows better radius on the journal. IMO a factory 421 or 428 crank is plenty strong. I'd upgrade to better main caps and studs though. Some(Eagle, K1) offer a 6.635 BBC rod that MIGHT help acheive zero deck as its only .010" longer than stock... The 6.7 and 6.8 BBC rods arent a bad choice though... Some builders will use a 6.535 BBC rod BUT its likely the piston gets a bit heavy...

3" main blocks have 1/8" more "meat" wrapped around the crank. Dont sound like much but when you actually look at the difference you can see it.

Still regret lettin my 440 go with a car I sold... its a good combo even with iron heads.

Keep the engine isolated from the chasis.

The 4 inch stroke crank in a 3.25 main in a 455 block should be fine, I ran one for 3 years in a dirt track car with no problems with cast rods and heavy TRW forged pistons. Ran it at 6000 RPM every lap. This was in the late 70s and there is a bunch of better parts now to let you lighten the reciprocating weight. A good oil pan and pump is going to be necessary for sure, factory pan is never going to get it done. Going to a shorter stroke will drop some of the bottom end that is a problem to hook up off of corners many times. Starting with a 455 block if you wanted to you could go .060 over making it a 446 cu. in. only 9 cubes less than a 455. An oil cooler and oil temp gauge will be help you keep it together. Accusump would also be a good addition.

The only recurring engine issue I've had is with stock Melling oil pumps and factory windage trays. The Canton tray took care of that, switching to a race pump next time it's apart.
I race my engines a couple of seasons between tear downs. Studded mains, forged rods and pistons. The only "Pontiac" parts are the crank and block. Aftermarket everything else.
Brakes, brakes, brakes. Never enough and never enough.
I re-wired all my electrical with only what's needed in a race car, no issues. No factory harnesses anywhere except the brake lights.
Transmission, a factory Muncie will die multiple times before you throw in the towel and get a racing trans. Factory aluminum bell flexes too much. Replace it before it breaks something else.
Power steering, smallest crank pulley and largest pump pulley you can get when running an OEM pump, been running it with a small cooler for 7+ years without any issues.
Run deep groove pulleys on everything.
Suspension, if running stock arms and leafs go to billet shafts and delrin bushings. Poly will be fine for track days, but not all out racing.
Solid body mounts.
A good radiator and aluminum water pump, no thermostat but a restrictor. Close off all air gaps.

Be prepared for weird things to happen to the car that would never happen on the street. I had a piece of tire rubber get lodged in the throttle linkage yesterday. Had to go back to the pits to figure out why the engine wouldn't get below 3000 rpms.

Vibrations rarely go away unless it's rubber buildup from getting offline, if it feels different come in and check it.
Do a bumper to bumper nut and bolt check before every event. If it bolts on it can break and/or come loose.
Replace motor and tranny mounts every couple of seasons regardless of how they look. They take a beating on the road course.

Maybe Bigger is Better will chime in - Won 3 Hill Climb Championships in a row 2009 - 10 - 11 etc. with a www.sdperformance.com built 455

Excellent info ho428, that's what I was hoping for, real world info.

Another big one is wheel lugs. Be surprised how many come loose or fail. Studs too.

Wheel bearings are on that list, crazy how those things go. The side loads the LeMans sees used to eat front wheel bearings, I'd be repacking them all the time, like at least twice a year. Thankfully the AFX spindles took care of that.

Axles and axle bearings. Eaten my fair share.

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WAR EAGLE would be VERY HIGH on my list of people to talk to about turning corners under high power with a 455 type engine.

Tom Vaught

I changed to 1/2" extended studs a long time ago, 7/16 is just too small.
Extended nuts aren't a requirement but I feel better with them on it.

If you run a c-clip axle and rear discs be prepared for a lot of brake pad knock back.

Thanks Tom - I like this vid were Bigger is Better Won this Competition beating out a 90-91 ZR-1 Vette

http://www.youtube.com/watch?v=P31VDlpXR9s

GREAT VIDEO! JOHNNY! You, "The Man" for sure on a course like that.

Like I said, you will not find many Pontiac Cars or Drivers with those skills. HO428 and our Down Under boat racer being in the same Skill Set club as Johnny.

Thanks Again.

Tom Vaught

I drove to the track, swapped all 4 tires for road race slicks, autocrossed the crap out of 455 with farily long courses(police driving academy site), then got into early NMCA and drag raced it for 2 years. Not as long a lap time as a full road course but it got beat on pretty hard and did fine, and it buzzed to 6000 shifts all day long-and with stock rods. The RAIV heads on it peaked close to 6000 on the dyno.

Johnny glad to see you post again. How is the body rebuild coming?

Great stuff guys! Thanks for the info! I've been doing NASA HPDE now since 2005, so I'm certainly not new to the issues at hand.

I've always been intrigued by the idea of a 440 pontiac, but what little bit of research I've read in to the subject seemed to suggest the factory blocks don't live long with that combination. Is that not the case?

Properly prepared, my understanding is there's no problem in the 650-700 range with a OE 400 block. (@ '67 - '71) . An additional .250 of stroke wouldn't add that much (440), and plenty of 4.250 stroke engines out there that survive abuse.



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Keep in mind it costs a lot more to do an engine that is destine for high RPM.

You could just use 'generic' 461 short blocks, have a spare on hand, and still be cheaper than one high RPM engine. Setup for the intended RPM range is really the only variable.

That way you can concentrate on the chassis and support systems, get that all ironed out.

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Agreed, the "race" engine should come last. Work everything else out first.

I ran an Iron headed 365 at first, added HRE heads for awhile, built a mild by some standards 407, used those same KRE heads and still running it.
The new 433 goes in after this season is over.

Over the last few years the brakes were upgraded, suspension, rims and tires sorted out, dual disc race clutch, Jerico trans and quicktime bell, Moser rear, and all support systems are pretty much done.

I definitely agree. Based on the information here, I'm going to put a new pan on the engine and look in to an oil cooler setup, then run what I have for a while. I can piece together some items in the mean time. If it lets go, I guess I'll just have to talk my wife in to building a new engine faster :cool:

There's certainly quite a bit on the car I need to sort from a chassis standpoint.

Hi Tom,

I think you have War Eagle confused with me ;) That said I have not posted in a long time so its understandable.

Jason just my two bits from my experience which is based on competitive autocross, track day, solo I (Time Trials) and hillclimbs. I list my experience as it is different then road race and it a term often miss-used. The big difference is in a Road Race your engine has to survive 40+ minutes of continuous hard loading/RPM cycles and all the other examples I listed really only have to survive say 20 mins of continuous hard loading.

I am on my third 455 engine (same block actually) and I have had really good reliability with them but have needed to focus on oil control (Canton Pan) and somewhat water/oil temps (bigger rad). In my current engine I shift at 6200 -6400 RPM but I can run it up to my rev limiter at 6800 RPM if I don't want to shift before a corner coming up. This motor has a forged crank and lighter forged rods and pistons which helped me get the rev limit up.

If the intent is to really road race then I think a smaller stroke motor would be more reliable and that would be what you see more with the other brands but I think the 455 can be made to survive with the oiling and cooling issues managed.

The reason I went with a 455, and I could have gone with a 301, 301T (did for many years), 350, 400, 455, was to maximise the power I could make and was not that worried about the longevity of the motor as I don't have those really long track sessions you see in road racing.

For the new car I am building (same motor) I will be looking at adding an oil cooler as I could get the water temp where I wanted it but the oil temp was still on the high side. I might consider an accusump as well but not really sure if I need one and I dont want to package it in the car as its pretty big.

Johnny

FWIW the Canton GTO pan is deeper but not as long, It can be extended to the length of the F body easily for a little more capacity and still not hang down below most headers.

Johnny - cool you chimed in - was planning on KNOX Mtn. this year - didn't notice you on the list for Racers in SP4 - without your 455 T/A its not the same

Roger Bolliger runs a 700 hp 496 long stroke bbc mains alu road race engine beating the crao out of it and out of his uponends(in two weeks we wil go to the Hockenheim ring to wach him race again) his engimne broke douwn twice one was a forged crank that snapt in halve. and afther changing the fireing order that was solved. one engine failer due to overheating rom a bad radiator with a to small watter return opening. sins then no more problems.
My own engine wil be a 700 hp 4 inch stroke bbc mains and 4.35 bore 7000 rpm
http://youtu.be/-Me_eLrG0ro
http://youtu.be/pv4qouMwhj8

So what kind of fuel system(besides a cell) do you road race guys run-mechanical pump?

I run -8 from the cell through a high flow inline filter to a RobbMc 550 pump, -8 with another smaller micron inline filter to a Pro Systems carb.
Keeping it simple makes it much easier to trouble shoot when something goes wrong.
Having the line with a hole in it inside the fuel cell turned out to be a pita to figure out. With a fancy FI system there's no telling what I'd have replaced running that down.

Regulator? If so dead head or return?

Also Roger runs Billet Cranks now - when your racing nothing to good for dependability