High performance motor build.

[rodman]

Will be sending the head out next week, installing bigger vales performance springs and vales shaving the head to gain more HP installing stage 2 cams hot street or mild competition, lumpy idle. This cam will make great power from 3000 rpm - 7200 rpm. Best with headers and larger carburetor. Specs: 288 duration, .410 lift.... port polish the head as well going to build the bottom end as well, new rods, pistons , mains caps so on..... I hope crank is not too worn I will buy a new one if I can find it.
setting the engine up to handle 75 shot NOS........
Few questions:

Dual carbs VS single.

Advantage and disadvantages ??

[BEEK]

what is your intent for this engine? street? hot street? autocross? full race?
what kind of fuel will you run? pump 93 octane? race gas?
are you looking for drivability?

what budget do you have?
all of the above have to be considered before i could recomend anything

[rodman]

what is your intent for this engine? street? hot street? autocross? full race?
what kind of fuel will you run? pump 93 octane? race gas?
are you looking for drivability?

what budget do you have?
all of the above have to be considered before i could recommend anything

Hot rod street and drive ability

[Danno]

75 shot? You are nuts.

[So Cal Mark]

what pistons and compression ratio are you planning on?

[vandor]

> I hope crank is not too worn

Fiat cranks are super hard, they rarely need to be reground, and only get damaged by lack of oil. Yours is likely fine, but needs to be checked by a machine shop.

If you want to use nitrous, then you'd better use billet rods and forged pistons (budget about $1400 for those two).

A single carb might be easier to set up for nitrous, plus you don't need the extra flow of dual carbs if you are using nitrous.

[rodman]

> I hope crank is not too worn

Fiat cranks are super hard, they rarely need to be reground, and only get damaged by lack of oil. Yours is likely fine, but needs to be checked by a machine shop.

If you want to use nitrous, then you'd better use billet rods and forged pistons (budget about $1400 for those two).

A single carb might be easier to set up for nitrous, plus you don't need the extra flow of dual carbs if you are using nitrous.

I already plan to use forged pistons and rods buy all new head bolts. shave the head add bigger vales . 10:5:1 would be optimal to run 93 octane 11:1 would require a higher octane....

[vandor]

Don't shave the head, they don't have much material betwee the surface and the intake valve anyways.
I would not go over 10:1 CR with 93 octane. I have 9.8:1 and it still occasionally pings on 93 octane gas.

[TulsaSpider]

I put a 1800 head on a 2L block and have had detonation issues.

[rodman]

Detonation occurs when excessive heat and pressure in the combustion chamber cause the air/fuel mixture to autoignite. Try a higher octane fuel. The octane rating of a given grade of gasoline is a measure of its detonation resistance. The higher the octane number, the better able the fuel is to resist detonation. Most engines in good condition will run fine on regular grade 87 octane fuel. But engines with high compression ratios (over 9:1), turbochargers, superchargers, or with accumulated carbon deposits in the combustion chamber may require 89 or higher octane fuel.

[sptcoupe]

I agree with Csaba on the CR. We have 10:1 in the coupe and it pings under heavy load with premium 93 octane pump gas. You''ll get better performance with a bit less compression and a more optimal advance curve than you will by having a bit more compression and having to sub-optimize the ignition advance map. Then there is always the issue of damage resulting from detonation.

[Danno]

You could run E85 with compression ratios close to what you are talking about. Not suggesting you do it, just saying it's possible.

[divace73]

You could run E85 with compression ratios close to what you are talking about. Not suggesting you do it, just saying it's possible.

Just a note on the E85, you have to ensure your fuel system (hoses, rubbers, gaskets, injector size etc..) are compatible
I have seen people get good results on the E85 but here in Oz it is somewhat harder to get than normal fuel and the car has to be tuned for it.

[DeanJones]

I agree with Csaba on the CR. We have 10:1 in the coupe and it pings under heavy load with premium 93 octane pump gas. You''ll get better performance with a bit less compression and a more optimal advance curve than you will by having a bit more compression and having to sub-optimize the ignition advance map. Then there is always the issue of damage resulting from detonation.

I have 10:1 compression forged pistons in my 1800 and still have pinging occur with 98 octane fuel! I would be careful about going any higher.

[Daniel]

I have 10:1 compression forged pistons in my 1800 and still have pinging occur with 98 octane fuel! I would be careful about going any higher.

This depends on what pistons were labled as 10to1 most of the vendors sold pistons for years under the impression
that they were 10to1 but were really over 11to1. I pointed this out years ago if you can find some of the old posts
on the topic. Many people are aware of this problem now and the older 11to1 pistons seem to be harder to find
these days. I think IAP is the only vendor still selling the 8mm domed pistons as "10to1" or at least last time i
checked.