Max boost? M90

2

200cid

Active member
What is the max boost you think the M90 could give and what is the max a rebuilt 200cid with ARP-bolts could handle? Just need something to get a scale of. How much can the stock -65 pistons take? Not like I´m gonna boost "all out" but just wondering.. :twisted: This post probably doesn´t provide enough info about the setup.. :roll: but I´ll provide more info if needed. Thanks
 
Well I think stock super coupes came from the factory running 12 psi. I don't see why 14 psi or higher wouldn't be possible. I am running forged pistons, so I after get mine all setup the way I want and run it for awhile at that level I think I may have to have another pulley made :twisted:
 
The generals are that if the advance is cut back to 28 degrees with inital timing of about 15 to 16 degrees static, and your engine has the Clifford port divider welded in and a good carb set-up which distributes fuel well, then you'll be able to hack 12 pounds okay. The compression must be around 8:1 or less.

Any 41 year old engine will 'crap out' eventually, as piston and valve guide and seal blow by can be huge with an old engine that has seen many miles.

The specifics are that there are 22 factors which influence the boost level you can obtain with a given engine with a given compression ratio.

Since turbo boost is gradual, a turbo will handle more compression than a supercharged engine. An intercooled engine will handle more than a non intercooled engine. An efi engine will hold more boost than a carb engine. An optimised, expensive electronic igntion system correctly mapped will allow a lot of boost to be made.

An early 200 log head with its stock 1.5" hole is not so good at flowing air fuel mix evenly to each piston. At high boosts, there is evidence a flow distribution occurs, especially on our I6's. It's worse with the early pre 1972 cylinder heads, and gets pretty good for 1976 to 1983 3.3 heads. The direct mount 2-bbl Holley/ Autolite carb conversion adaptor pioneered by the writers of the Ford Falcon performance handbook is very good at adding lots of air fuel mix without any problems with restictive airflow causing some cylinders to be underfed with fuel, others to get too much. That;s the worst situation for preignition of detonating happening.

An engine with stock pistons or stock engine will be able to handle a lot of boost before it blows up, because is only designed for a 300 hour dyno test on a stock engine. If you supercharge or turbo it, you change the load the engine sees at the pistions.
 
xecute you have way too much knowledge, why don't you donate some of it to me?
 
xecute®™© he he":1sjmthmy said:
An early 200 log head with its stock 1.5" hole is not so good at flowing air fuel mix evenly to each piston. At high boosts, there is evidence a flow distribution occurs, especially on our I6's. It's worse with the early pre 1972 cylinder heads, and gets pretty good for 1976 to 1983 3.3 heads. The direct mount 2-bbl Holley/ Autolite carb conversion adaptor pioneered by the writers of the Ford Falcon performance handbook is very good at adding lots of air fuel mix without any problems with restictive airflow causing some cylinders to be underfed with fuel, others to get too much. That;s the worst situation for preignition of detonating happening.

An engine with stock pistons or stock engine will be able to handle a lot of boost before it blows up, because is only designed for a 300 hour dyno test on a stock engine. If you supercharge or turbo it, you change the load the engine sees at the pistions.
Click to expand...

Do you think my C-5 head will restrict too much? Will it be okay with a Holley 500cfm or such? Gonna go with the stock pistons. what kind of a camshaft would be good?
 
Analyse the things you are perpared to do to give your engine a better chance of living a long life. Put a dollar and time value beside it. You can't go into all the 22 modifications to improve the chances of suvival, but you can do some basic things.

All stock Fords have marginal pistons and rod bolts, and little sixes before 1971 have poor head flow.

You can add an adaptor and clean the C5 head opening up, and that will be nice and cheap and effective.

Preferences should always be for the D8 onwards head.

Air flow is air flow. Any improvement is better than none. Plenty of info around. The fuel has to be well mixed and everything done to keep the instillation simple and free of pinch points. Like the stock 1.5" hole in the manifold. If you added a Stovebolt or Clifford adaptor, you are going to help ram air fuel mix in there. Remove the under carb inlet heating, and you reduce your octane rating requirement by a few numbers, and avoid detonation from excessive intake manifold heat.This comes from the exahst under it, and it has been a proven way to need 8 octane numbers more on your fuel on some engines.

The boost level will increase ring blowby. At 5000 rpm, a stock engine might yield 3 or 5 cfm of blowby into the crankcase and block. It may only be 1% of the air flow on the stock engine, but will be twice as much with 14 pounds of boost.

With a supercharger, even more more blow by will go past the rings, creating ring flutter which breaks ring lands and further dilutes the air fuel mix. Rule out any 5000 rpm trips with a supercharged stock engine.

Unless its a brand spanking knew item, an old engine is a liability unless its build to take it. The engine will work well if its not over reved. The basic engine is able to take a huge boost without breaking things. 450 flywheel hp is possible if the right rod bolts and pistons and anti detonation stratergy is used.
 
I am up to 103 in the 1/4 mile on a lot of boost, all with stock internals
(high mileage angine, also)

Does 10's is also running stock pistons.


.
 
My machinist will clean up the head and do what he can. A better head is out of the question because here in Finland we don´t have them.. Not going for crazy hp-numbers here. Just something around 200+ from flywheel. I guess electric fuel-pump, MSD-boost controller and a rev limiter are needed..?
 
We normally run 17lbs. of boost on cast pistons.
With that being said......we did burn up #6 a bit. That cyl. is just running hotter (leaner) than the other 5.
So we're installing forged ones as we speak. And we'll be doing some stuff to eliminate the hot spots!
Later,
Will
 
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