Effects of performance modifications on engine life.

T

Tugmaster

Member
I was wondering if doing performance modifications will have a negative effect on the life of my engine. I am building a hopped up 30 Coupe. I know this site is more geared towards purists but to me it is "ground zero" when it come to Model A knowledge.
Here are my plans, 5.9 head, lightened flywheel, mild cam, downdraft carb and header. My motor is rebuilt with zero miles. It still has babbit bearings and stock lifters. I plan on pulling the pan and checking the bearing clearances since I don't know who rebuilt the motor. I did do a compression check ( cold motor)
It was 58, 58, 65 & 60.
I am new to A's and don't want to mess it up. Just want some more pep. 99% of my driving is on country roads under 60 mph.
Any constructive thoughts?
Thanks, Todd
 
Hi Todd, it has been over 4 hours since I first read this and I see that no one has posted so let me just offer it this way. Modifications are not the only thing that causes engine failures. It can be the way the engine is operated that causes the problem too.

If the engine was poorly constructed (improper pouring of Babbitt, incorrectly grinding the crankshaft, poor machine work) and you are adding those items, sure it will probably exacerbate the upcoming "death" of the engine. If the engine work was done correctly and the vehicle is driven sensibly, the items you mentioned will not have any adverse effects on longevity.
 
i got here late because of the long week end,but power has its price, any time you increase engine power over the original design specs you take the risk of engine failure, the best protection is to use the higest quality parts availabe, and the best machinest and shop you can locate, doing those two things will minimise any risk of damage and contribute to long engine life
 
My 30 coupe is running a 33 B engine with the original bearings & std crank shaft,Only mod is a 5.9 head.after 14,000 miles it runs perfect & uses no oil between 1,000 mile changes.It has around 60 HP & has all the power that I ever need.I have a Columbia OD with 4.11 gears for great power in std ratio & can pull most any hill up to around 8 % grade ,if I can get a good run at it.
 
It is important not to "lug" the motor. Knowing the power curve and driving in the "power range" is probably more important to engine life than the modifications.
 
run it the way you want . all it can do is blow up . normally you will get bearing knock before it comes apart . as said , if its a good rebuild , no harm will come if not abused .............
 
Well, you've found out that if you ask 10 Model A guys a question, you will get 12 different answers! The performance mods you are suggesting will have little to no affect on engine life. Think about this, when cruising down the road it takes X amount of power to run a certain speed. It makes no difference on engine life if this amount of power is achieve with 4:1 compression or 8:1 as the cylinder pressure is the same in order to make that amount of power. Any extra stress would come when you have your foot in it, as on a hill. The A has as much bearing area as the early Chevy-6 which was used until about 1950, so will hold up well if done correctly and not abused. Do not lug the engine, or let it detonate. These engines were raced successfully for many years, and held up well. Just do it and enjoy!
 
IMHO someone who makes major mods to the engine is more likely to take the car to it's limits. It would seem to me that this would shorten engine life.
 
Yeh, the thing about performance mods is that you start to like and use them. However, Jim Brierely has used babbitt mains on his Bonneville engine for many years. The A can take it. The most important thing of all for long engine life, stock or modified, is proper assembly. Measure everything, twice.
 
columbiA said:
I might add,It will pull most any hill up to about 8 % grade in OD if i can get a good run at it.
Click to expand...

I have a Columbia two speed rear member, it's a '41. I would like to put it in one of my A's. I'm assuming that you've done that. What did you encounter?
 
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