Talk me out of this, 3.0L or rebuild my 2.7L

[kent olsen]

My original intent was to bring my 72T down to a weight that would be easy to have a 10:1 power to weight. I've got the weight down to 2200lbs, this is a street/autox/DE car.

I've been seriously looking at going to a 3.0L for more torgue, problably longer lasting and possibly (3.2L cylinders) able to run regular gas. Wayne's book encourages me to go the 3.0L route.

However I now have a 74 2.7L engine that was rebuilt a number of years ago, I believe I have 60K+ on it now with no major problems. Soo my question is how much, in comparison, would it take to build my 2.7L up to around 230hp. also I'm assuming that much hp would require premium gas and maybe twin plugs.

I have 40mm webers and European headers/M&K muffler which will stay in either case.

This is my winter project to start after Christmas, what do youall think????

[sww914]

If It were me, I'd build the 2.7 to RS specs. 9.5:1 compression, RS cams or maybe a little bigger, 36mm intake ports, 35mm exhaust, and you're right there at 210-220 HP. At 60K I'd leave the bottom end alone if the case has already been fixed.

[kent olsen]

Yep I've been thinking that way. I liked the Mag case because it's lighter than the aluminum and weight is what I've been removing as I go along.

I'm curious how long a built 2.7L that gets a lot of use will last. I know the 3.0L lasts forever. Also if I try to squeeze a little more compression it will mean twin plugs and I understand the distributor is really expense and hard to find. Since I don't care about originality I don't have a problem using some other type distributor.

So maybe a little head work, 9.5:1 pistons and a little more agressive cam might do the trick?

[sww914]

That's what I'm doing with mine. I'm not going higher compression to increase longevity/durability and so I can avoid spending thousands on a distributor. My race budget is limited, it's pretty much the last thing n the list, so I can't afford to take an engine apart twice a year to refresh it. I already have to work enough weekends to afford racing as it is. I know that I'm leaving a few HP on the table not twin plugging, but those are the expensive few HP. The head work might not even be necessary, mine already has 35mm ports and my friend is doing his heads to 36mm at his machine shop, so I'll do mine at the same time.

[J P Stein]

I ran my 2.7L with 9.7:1 pistons, Solex cams, Webers for 7 years. Street time/AX/one DE early in it's life then AX only. It worked fine on 92 octane. It would have still have been going had I not overlooked checking the ring gap at initial assembly. The usual upgrades were done to the case at Dan Hall's in Portland.

Scored cylinder walls caused loss of compression and gave me an opportunity
to spend a bunch of money on new P/Cs and freshen the internals......which were very nice.

You're going to need Nikasil cylinders to change pistons....if you haven't those now. EBS will replate cyls for 150 a pop.....dunno if they can do the Alsuil to Nikasil tho.

[kent olsen]

JP

Do you know how much hp you were making with that combination?

[J P Stein]

Originally Posted by kent olsen

JP

Do you know how much hp you were making with that combination?

Never had it dynoed. I figured an honest 200 at the flywheel. The butt dyno says it has a wide power band, super for autocross and yes, a light weight car helps.
HP works only when you're OTG. Light weight works all the time.

The rebuild will be finished off tomorrow. I'm figuring to get it broke in on a engine or chassis dyno ......mostly to get a A/F reading.....race gas is new to me.

You're burnin' daylight. The first ORPCA AX is March 2....I'm hoping it don't snow that day.

[J P Stein]

Done.....or woulda been had I not buggered up the threads of the fan nut.
Anybody got one? .......

[JohnJL]

ughhhh! Isnt that a bear....everything is done and spoiled by a $1 bit!

[HarryD]

JP,

Nice lookin' engine.

[Robs72T]

Kent, I've been debating the same thing as you..... and I also have a 72t


I think part of the value of the narrow bodies is keeping it near "period correct", that and with people having the tendency of making RS clones adds up to keeping the 2.7 in the car. I know this doesn't address your torque/power question, but if you want more power then why stop at 3.0???

Again, I would keep the 2.7 in the narrow body.

Originally Posted by kent olsen

My original intent was to bring my 72T down to a weight that would be easy to have a 10:1 power to weight. I've got the weight down to 2200lbs, this is a street/autox/DE car.

I've been seriously looking at going to a 3.0L for more torgue, problably longer lasting and possibly (3.2L cylinders) able to run regular gas. Wayne's book encourages me to go the 3.0L route.

However I now have a 74 2.7L engine that was rebuilt a number of years ago, I believe I have 60K+ on it now with no major problems. Soo my question is how much, in comparison, would it take to build my 2.7L up to around 230hp. also I'm assuming that much hp would require premium gas and maybe twin plugs.

I have 40mm webers and European headers/M&K muffler which will stay in either case.

This is my winter project to start after Christmas, what do youall think????