Most power out a Nord Engine Naturally Aspirated - Page 2

Grant · #16 (**permalink**) 04-22-2008, 03:29 PM

Hey, is a Fiat twin cam engine a better design for racing than the Nord? It is more of a pent roof, if I'm not mistaken. Anyone know a bit about the Fiat engines?

I rode (actually I drove it too) in an early 70's spider with a Guy Croft head and dual side drafts...it was pretty fast.

raff_gta · #17 (**permalink**) 04-22-2008, 07:25 PM

ive actually got a fiat and yes, the motors are a better design. The lampredi engine was one of the most influential designs ever, but remember that the Fiat engine came along almost 15 years after the Alfa one. Everything on the Fiat Twin Cam has been thoughtfully designed; the head is pretty good, flows well, good chamber design, and the bottom end is solid as (forged parts from factory depending on engine). And then theres the integrale 16V...

raff_gta · #18 (**permalink**) 04-22-2008, 07:35 PM

Quote:

Originally Posted by genericwood

Raff, our Nord engines are relatively long stroke. The piston speeds can get really ridiculous at 8000+ rpm. Most race engines are running aftermarket rods which can handle it, but both rod and main bearings get very short-lived if you are going to go much higher. Of course, this assumes that you are running lightened valve gear and really good springs.

You are correct about the combustion chamber shape being poor. When you start getting the compression you need to make big power, the shape gets even worse. But the other big limitation is the port angles. It's really tough to get the mixture to turn the corner to fully utilize the valve size.

Erik

**Alfar7** · #19 (**permalink**) 04-22-2008, 08:48 PM

Quote:

Thats the other thing I've been told, that the 2 litre has too large a stroke to rev hard enough to make more power with the standard head.

awesomeBLT · #20 (**permalink**) 04-29-2008, 10:14 AM

Quote:

Originally Posted by JoeCab

Yes, that is about the limit. Here's a dyno graph of a pretty serious 2 liter.

Gordon Raymond · #21 (**permalink**) 04-29-2008, 06:50 PM

Richard and Eric have the background knowledge here. I spend lots of time restoring the odd collectable parts for some of the old NORD race engines. The design WAS state of the art in 1955. It is now 2008, and quite a few new ideas have been generated in the past 53 years. I have been driving my '65 Ausca GTA engine on the street now for years. In May of '74, after a rebuild, it had 167 Hp @ 7500 on Ron Neals dyno. Between 7000 & 7500 it lost it's 2nd pound of oil pressure. Torque had dropped from 118 @ 6500 to 112 at 7500. It was done. Sure, with todays titanium valves and my new cams from Richard, I can wind it higher, but there is nothing to gain.
With a 2L, as Richard suggests, you have added more piston weight, and a even longer stroke. That will not help it build power at 8,000 RPM + with the existing head design. Even with the best of current internal components, the 2L, 50+ year old design has it's limitations. Failure to recognize this can be just another expensive mistake.
Re - read Eric's post. It's FACT based on experience.

awesomeBLT · #22 (**permalink**) 04-29-2008, 10:54 PM

I have to say 220hp under 7500 RPM is very appealing. I also have to raise my hand as one of the folks stuck in 1967, however I am trainable.

B

AR67202 · #23 (**permalink**) 05-01-2008, 01:17 PM

My stock 2.0 TS (AR67202, 90mm stroke, 84mm bore) got dynoed at 164.5 Bhp at 6300 RPM and 213.8 Nm at 5200 Rpm a few years ago. I fully recognise this engine has a better head design compared to the twincam though, but heard some rediculous claims that it's "very expensive to get more than 175 bhp out of an 8v twin spark engine".

I'm now in nthe process of rebuilding it, and aiming well above 200 Bhp without going to extreme RPMs in the process... I'm firmly under the impression these engies got deliberately limited in power output by the factory, by undersizing the injection system (motronic M1.7)

I still have a lot of questions for you guys though, seems like the best place for information about these older engines

Sprintn · #24 (**permalink**) 05-07-2008, 04:44 PM

Alfar7
BUT... If you cut the block and shave the head... aren't you also redusing the displacement... say from 2 liter to 1950... or less? Not sure how much cutting you are doing. WIll the stroke be shortened enough so that the engine will be able to spin fast enough to compensate for the smaller displacement??? I know there are other variables but... will that be enough?
Sprintn

PSk · #25 (**permalink**) 05-07-2008, 06:07 PM

Quote:

Originally Posted by Sprintn

Alfar7
BUT... If you cut the block and shave the head... aren't you also redusing the displacement... say from 2 liter to 1950... or less?
Sprintn

180OUT · #26 (**permalink**) 05-07-2008, 06:20 PM

Quote:

Also does anybody know what Cosworth do to old Jaguar straight sixes to get them to produce like 50hp more than they used to back in the 60's?. These engines are very similar in head design/porting, combustion chamber and long strokers like the Nord engine. Lightweight E-Type Jags now blow Ferrari GTO's away which was not the case in their day ... thanks to modern engineering fncking classic racing

.

Sprintn · #27 (**permalink**) 05-07-2008, 06:23 PM

Yes... i agree... but in the context the reply was written... following on something about a nord engine not being able to turn quickly due to its long stroke... and him saying to cut the blocks... it almost sounded as if he was suggesting to cut the block enough to actually HAVE to shorten the stroke.

Crazy but I guess it would be possible.?.? But yes... I also agree that shaving the head would be done to increase the compression.