New Dyno Numbers

[1 fast z]

wow, that is a well thought out system. What clutch disk material are you using? Is it OK on the street?

 

If I did the math right, you're only running .024" piston to head clearance... is that right?

 

Thats 2 thou too much

[MONZTER]

Thats 2 thou too much

 

oops

[240hoke]

Good lord your engine sounds good...I havent heard a N/A L sound that good before. I used to the muffled roar of a l28et. Congrats on the numbers I am always impressed by your work!

[wigenOut-S30]

dude.. just amazing work! It sounds fantastic and I bet she hawls

 

[MONZTER]

wow, that is a well thought out system. What clutch disk material are you using? Is it OK on the street?

 

 

The clutch uses Kevlar disc so not as light switchy as the bronze. It is OK for the street, just takes a little getting use to it

[RB26powered74zcar]

My impression... WOW!!!

[Daeron]

If I did the math right, you're only running .024" piston to head clearance... is that right?

 

Thats 2 thou too much

 

beat me to it

[John Scott]

I'm starting to have doubts, please don't take it personally...

 

I have a friend who built a stroker with similar compression, had the head professionally ported by a good shop, tried changing cam timing and ignition timing and couldn't get over 180 whp with that cam on triple 44s. In fact I know several people who have bought that cam and changed it out because it's too small.

 

Have you ever had this engine dynoed before (on a different machine)? After finding out you're running the stage III cam, I'm thinking the dyno you were on might be a wee bit optimistic...

 

Just a thought, but instead of using a dyno, if possible find a sanctioned 1/4 mile track. mph is a pretty reliable figure for figuring wheel horsepower, real live moving the car number, compared to sitting on different dynos and type variences. Even with limited traction the number can be put back through the calculators and spit back a relavant number. If nothing else more proof for the claim.

 

for a 2500(?)lb car, 231 hp = 105.79 mph. Give it a try!

 

Nice engine bay, sweet sound!

[JMortensen]

I'm thinking that Jeff may be right. You can just listen to his engine and compare it to others built with that cam and there is obviously a huge difference. I still don't get WHY there is such a difference, but there is. Jeff, I think you should build a EP legal motor and see what you can get out of it. If you're 50 hp above what Sunbelt can do, I expect you'd get some engine orders pretty quickly.

[Tony D]

Some people get 147 to the rear wheels on an L28 stock build, and the engine runs out of steam at 5600.

Others make considerably more using the EXACT SAME components and have a power peak at 6500.

 

It's all in attention to detail, and biasing things to work properly. A lot of people have no idea what or how things actually work together inside and engine---and think 'assembly is assembly' and put components together then wonder why they are 'down on power' compared to the same components someone else assembled. Worse yet, they think that the factory settings are the ONLY way to assemble the engine. And if you do it that way, likely you will have very close to a stock engine. But if you know where to move this, and realign that....where to polish and clearance, where to rin a tighter clearance...all those little things can add up cumulatively.

 

Sometimes the differences can be STARK.

 

Sure, dyno differences can account for some of it, but I have had people get out of their cars and start swearing at me because my rat-trap POS 75 2+2 is a FULL SECOND FASTER consistently in the 1/4 mile than their pristine 75 Coupe with headers, big throat throttle body, performance exhaust, blah blah blah... Guy started swearing at me and claiming there was NO WAY I was that fast without a CAM in it!

 

We are talking a consistent 15.45-15.50 1/4 mile against his 16.45-16.67 times.

 

2695# on my car, at a trap speed of something like 89mph. I got the slips somewhere.

 

"It's not possible"...yet it occurs.

 

And if you saw the car (some here have at the various National Conventions) you would swear to if my rattle-trap POS was a second faster than your shiny sporty Coupe! Who needs shiny paint? Unless I'm at Bonneville, I don't polish nothing! LOL

[ckolander]

There's just no way that your POS 2+2 is that fast without shiny paint and racing stripes. Everyone knows that the only proven method of making your car that much faster is with paint and racing stripes.

 

All that technical engine mumbo jumbo don't mean nothin if you ain't got the bling bling to back it up, yo yo.

[JMortensen]

It's all in attention to detail, and biasing things to work properly. A lot of people have no idea what or how things actually work together inside and engine---and think 'assembly is assembly' and put components together then wonder why they are 'down on power' compared to the same components someone else assembled. Worse yet, they think that the factory settings are the ONLY way to assemble the engine. And if you do it that way, likely you will have very close to a stock engine. But if you know where to move this, and realign that....where to polish and clearance, where to rin a tighter clearance...all those little things can add up cumulatively.

You keep saying the same thing Tony, as if I'm comparing what Jeff did to something built by a half-witted idiot in their garage, but that's exactly what I'm NOT doing. His motor makes A LOT more than a Sunbelt EP engine (using hp specs per Coffey), and makes hell of a lot more hp/liter than the motor that was built for the Bob Sharp car. It makes more than Rebello's engines (even at his suspiciously high bhp numbers). My point is that there is an explanation for it, and I'm not chalking up a gigantic hp increase to "polishing this and tweaking that". All of my examples I've listed use carbs. It could be that the carbs are a choke point for the intake. I'm pretty convinced that there needs to be a fundamental difference in order to get a hp bump of that magnitude. The only thing that it could be seems to be the carbs. That's why I said I'd like to see what he can do in an EP legal build. If the numbers remain that high and if he can transfer his advantage from engine to engine (not much market for Z engines anymore), I think he'd get a lot of business building race engines.

[z-ya]

Jon,

 

I don't think that the carbs will limit peak power (and that's what we are talking about here). Basically that is all you can tune with carbs. EFI will get you a consistent AFR across all RPM and loads (if tuned correctly). You can't do that with a carb, but you can tune for peak power. I can't imagine that a single TB EFI intake can flow more air than a set of Mikunis or Webers.

 

Pete

[JMortensen]

I don't think that the carbs will limit peak power (and that's what we are talking about here). Basically that is all you can tune with carbs. EFI will get you a consistent AFR across all RPM and loads (if tuned correctly). You can't do that with a carb, but you can tune for peak power. I can't imagine that a single TB EFI intake can flow more air than a set of Mikunis or Webers.

I like Flexicoker's sig line, which is something to the effect of "Racecars, unlike women, must eventually respond to reason". He's doing SOMETHING right...

[MONZTER]

Every once in a while even a blind squirrel finds an acorn HAHAAHAH

[bradyzq]

Your power numbers represent at least 275HP crank plus or minus fudge factors.

 

To compare, your wheel numbers are within 10 of a stock 350Z's, and that's supposed to be a 300hp motor!

 

Basically, WOW.

 

Sounds great too. I aspire to that sound for my Z, but with triple Weber intake moan thrown in.

[col]

Are you sure the cam is as labeled?

I have been sent a cam that was not as described.

Maybe you actually have a bigger cam than you think.

[Tony D]

Jon,

 

I don't think that the carbs will limit peak power (and that's what we are talking about here). Basically that is all you can tune with carbs. EFI will get you a consistent AFR across all RPM and loads (if tuned correctly). You can't do that with a carb, but you can tune for peak power. I can't imagine that a single TB EFI intake can flow more air than a set of Mikunis or Webers.

 

Pete

 

This would come under my definition of 'performance maximization'...

 

Recall we gained 40HP on the Bonneville car by swapping to EFI and ITBs from identically sized Weber DCOE's. Even our dyno operator said it "You could have gotten that power with 55 Webers, but you wouldn't have had the reliability without the crankfired igniton."

 

It's all how you define tweaks and polishing. I never said idiots. I said some people just don't think any variation from standard assembly tolerances is acceptable. We put the Bonneville engine together in a Home Garage in Clairmont. It was covered with a Hefty Bag when we left for the evening. This stuff isn't rocket science, but there may be a bit of art to it.

 

If you are searching for a concrete quantification or scientific explanation, I proffer you won't get one. That would put his setup into a Factory Assembly Manual mode---the next guy goes and follows all the exact same dimensions (lets say to 5 decimal places, for argument), follows the same component list, and then yields 20, 30, 40 HP less.

 

How do you explain it?

 

Many of these EP gurus you speak of, do they punch out the engine and warranty how much power it will make before putting it on the dyno? Unlikely, they will give you a 'range' and if it's not up to their liking, it comes back apart. If it is, they go 'whew' and send you the bill.

 

But until it goes on the dyno, even knowing every component is what it's supposed to be...they don't know for sure till it runs!

[JMortensen]

If you are searching for a concrete quantification or scientific explanation, I proffer you won't get one. That would put his setup into a Factory Assembly Manual mode---the next guy goes and follows all the exact same dimensions (lets say to 5 decimal places, for argument), follows the same component list, and then yields 20, 30, 40 HP less.

 

Eh, I'm not buying that argument either. Reminds me of the Top Gear story on the GTR where I think Jeremy Clarkson said the motors were hand built and so they couldn't quote the hp within + or - 40 hp. If you can't track it down within + or - 40 hp, then your tolerances are too loose and things need to be tightened up at the factory. That's my take on it.

 

If you build the same motor twice, to use your example down to 5 decimal places, it should make the same power, within a very tight range. The further the resolution on dimensions go, the tighter the power range should be on the final product. I'm not buying that there is some magic power fairy inside the engine that makes this one do one thing and that one do another. If that were the case, the idea of spec racing classes to keep costs down would be stupid because you'd have to keep building the same engine over and over and over in an attempt to get a "lucky" +50 hp to have an advantage over the field.

 

EDIT--Maybe it's all about Bryan's super tight head to piston clearance...

[z-ya]

 

Recall we gained 40HP on the Bonneville car by swapping to EFI and ITBs from identically sized Weber DCOE's. Even our dyno operator said it "You could have gotten that power with 55 Webers, but you wouldn't have had the reliability without the crankfired igniton."

 

We are talking about air, and whether it is from triple Webers or ITBs, doesn't really matter. Yes, with EFI you can tune across all load and RPM points. With carbs, you have limited adjustment, so adjust AFR for peak power at the RPM range that makes the most power for YOUR engine. It is not rocket science or magic. It is just a matter of finding the sweet spot and adjusting AFR and timing for max power while minimizing detonation. Again, we are talking PEAK power, not average across all RPM and load points. So a set of Webers will absolutely produce the same PEAK power as ITBs given the correct tune for that motor.