Safe red line, how long lasts an engine ?

[alpa]

Hi,
I'm collecting information for a possible 124 purchase.
I could not find an answer to the following questions:

What's the safe red line of a stock 1.6 engine ? Are there known weaknesses ?
What's the average mileage when the Spider engines need a bottom rebuild ?
And combining both questions above: what's the average mileage that would safely allow me to rev high a 1.6 ? Is it safe to assume that say a 100k miles engine will survive if I rev it hard as a "fast" street car (assuming performance cams) ?

I'm able to do any mechanical work but right now I live in an apartment, it's difficult to rebuild an engine on a park place .

Thanks

[So Cal Mark]

the harder you run it, the shorter its' life will be. So, run it as hard as your budget will allow. If you can't afford to repair it constantly, use some discretion. Over revving doesn't help performance if the power curve is dropping off.

My approach is to only run it as hard as I need to for any given circumstance. Why rev it to 7k to get to the next stoplight? That serves no purpose other than to wear out parts

[alpa]

I'm not a red light racer, especially in town. I like playing when there is nobody, or on the track.

If I don't go the turbo road I'll certainly use some good cams in order to have power, which means revving as high as possible. That's the reason of the question: how high can I go ?
Say if it's 7000RPM then on 1.6L I should be able to reach 140hp. If it's 6000RPM, well, I'll go turbo or ... 300zx TT.
Turbo means not to use 1.6, CR too high.

PS: I'm also asking these questions to decide which version and in which condition to look for.

[mdrburchette]

Redline on a 1608 (1.6L) is 6500 rpm. There are not many reasons to drive it passed the redline under normal circumstances and these little engines are rev happy, but like Mark says, the power curve will drop before redline. Here's a dyno of my 1608 before an engine rebuild. You can see the torque curve and power band starts dropping after 6k rpm:


With that said, if you want more power and durability out of your engine, just changing cams won't get it. I sunk a lot of money into mine to achieve a happy balance between driveability and performance. Dual IDFs, 42/82 cams, GC racing springs, ported and polished head, port matched intake, custom flywheel and clutch...and everything balanced, so I can rev it up to 8k rpm, but even with all of this, the power band falls at around 7200 rpm and I rarely drive it hard like that unless I'm autocrossing it.
One thing to remember is when going with bigger cams, you may lose a little bottom end power. I notice a kick in the pants around 4k rpm with my setup, but have good power through the whole rpm range.

[alpa]

Thank you for your reply.
Which cams did you use or try ?
PS: now I see the picture. It's a -6000 cam, not a 7000.
PS2: Oh sorry, you gave the cams. Strange !
Sure if the power is above 7000 you can not have decent torque under 4000 on a 2v non VVT engine. It may be possible with the Alfa Bialb, but it's a totally different engine.
I've already had a look at Fiat cams. I'm surprised by a high overlap along with a low duration. Even if it was common on carb engines I don't think it's a good solution because too much overlap kills bottom end and too low intake closing kills high revs. Fortunately it's a TCam, so these numbers can be moved.
I found Kent make cams for 8v, but still with roughly the same specs. I'm not a Kent cam fun.
The only good compromise I found are Colombo&Bariani Road Medium. Probably good cams for a 6500 red line. Their Race medium is certainly unusable on the road, too much overlap (4mm at TDC).
I think I'll do another thread about cams.

Question: is the cam timing adjustable on std engines ? Like on Alfa cams ?

[mdrburchette]

Kent Cams makes adjustable cam pulleys if you want to play with cam timing. If you're planning to go all out on an engine rebuild, reducing rotating mass where you can sure plays a big roll in lower end torque.
I'd also try emailing Guy Croft on cam choices. He makes cams for different applications and may be able to determine which would be right for what you want. I'll be getting a set from him soon.

[So Cal Mark]

Jason Miller at Miller's Mule is also making adjustable pullies, much cheaper than Kents' units, and he's in the USA

[mdrburchette]

You're right Mark. I forgot about Jason.

[alpa]

I've already asked the price at Miller's Mule.

mdrburchette
I find strange your power/torque curves, they look very standard. Numbers are rather low as well, but US gas has lower RON, so perhaps that's the reason (regular is 95 in Europe).

Look at Alfa 75TS curves I measured on my stock car. Torque curve is similar to yours. Torque values are on the left side, N.m. It's a 8v 2L Bialbiero engine with 2 spark plugs per cylinder, I'd expect it to flow roughly the same as the Fiat except for higher output numbers.

[mdrburchette]

Mine would look standard since this is on my original 1608 with 120k miles on it. I believe this was the first time that engine was ever run past 5000 rpm...I just knew it would just blow to pieces during the test. Yours does look quite similar. I would post the dyno results on my new engine but I had a fuel mixture and ignition signal problem when I dynoed it. I'm hoping to have it retested again this year.

[baltobernie]

Denise, are your numbers RWHP from a chassis dyno, calculated engine HP from a chassis dyno, or directly from an engine dyno?

[mdrburchette]

It's taken from the rear wheels. Pitiful numbers when you look at it that way, huh? The new engine was around 100 hp at the wheel even with all the problems that popped up.