Search found 2618 matches

by hoffman900
Mon Mar 18, 2024 4:03 pm
Forum: Engine Tech
Topic: My CompCams Cam Card ECL Question
Replies: 13
Views: 370

Re: My CompCams Cam Card ECL Question

Roundybout wrote: Mon Mar 18, 2024 1:06 pm That’s pretty close. I wonder if any perceivable difference would be even measurable on a dyno between those two specs. Probably within the margin of error to be even picked up.
I bet actual running duration changes 5-10* from spec’ed just by virtue of system flex.
by hoffman900
Wed Mar 13, 2024 8:02 pm
Forum: Engine Tech
Topic: Pushing the limits of a BMC A series head - max effort circuit race
Replies: 17
Views: 953

Re: Pushing the limits of a BMC A series head - max effort circuit race

KnightEngines wrote: Wed Mar 13, 2024 6:20 pm
Erland Cox wrote: Wed Mar 13, 2024 6:18 am How much less hp will an engine with dual SU carbs give?

Erland
No idea!
All the ones I've dealt with have run a Weber.
Split Weber or single on a manifold with bends?
by hoffman900
Wed Mar 13, 2024 10:07 am
Forum: Engine Tech
Topic: Anyone been able to reach Isky Cams lately?
Replies: 29
Views: 1988

Re: Anyone been able to reach Isky Cams lately?

Hi. I’ve contaded them by email and on their facebook-page 3 times for about 6 and 3 months ago, without any reply. Asked for help with a part number. In the end I figure it out, but I still invested my cash in Jesel- parts instead. Email and social media are probably the most unreliable ways to co...
by hoffman900
Wed Mar 13, 2024 9:22 am
Forum: Engine Tech
Topic: Pushing the limits of a BMC A series head - max effort circuit race
Replies: 17
Views: 953

Re: Pushing the limits of a BMC A series head - max effort circuit race

How much less hp will an engine with dual SU carbs give? Erland According to the builder I know, 145bhp or so is the limit on those carburetors. That includes all the tricks: thru-boring, etc. He did a big cam development round and was stuck there, changed to the FI and the differences showed thems...
by hoffman900
Tue Mar 12, 2024 9:40 am
Forum: Engine Tech
Topic: Honda CBR1000RR stock valveseats.
Replies: 4
Views: 274

Re: Honda CBR1000RR stock valveseats.

Mike, have you mapped out the valve timing on these yet?

Not surprised by some of this. Bikes, even racing, run under a lot of part throttle time, and would be focusing on mixture motion for better part throttle combustion quality vs outright flow / max WOT power.
by hoffman900
Mon Mar 11, 2024 9:25 pm
Forum: Engine Tech
Topic: Road Race Build .. input required
Replies: 12
Views: 618

Re: Road Race Build .. input required

E85? . I would go 3.48 to keep c/r reasonable. If it has a big enough tire and the best passing is coming off a slow corner a 406 might be hard to beat . Just to be different, a stock block 350 with lite wieght parts will be about 50lbs liter than a 406. E85 is a “how long is a session and how big ...
by hoffman900
Mon Mar 11, 2024 5:15 pm
Forum: Engine Tech
Topic: Road Race Build .. input required
Replies: 12
Views: 618

Re: Road Race Build .. input required

I don't think I would run pump gas under those conditions. AV gas might be a good solution. Plenty of SCCA classes require pump gas, and do fine. Most amateur endurance road racers use pump gas because of costs. Almost all FIA race series in Europe require 94-100 octane fuel. I think OP needs to be...
by hoffman900
Sun Mar 10, 2024 8:43 pm
Forum: Engine Tech
Topic: Most aerodynamic Muscle Cars?
Replies: 69
Views: 6062

Re: Most aerodynamic Muscle Cars?

From a pure driving experience stand point, a manual is the most rewarding / fun. If the car is a fun toy, and you’re not worried about consistency for bracket racing and or have some kind of physical handicap, a manual is absolutely the way to go. Do I judge when I see a cool car with an automatic?...
by hoffman900
Fri Mar 08, 2024 9:47 pm
Forum: Engine Tech
Topic: Pushing the limits of a BMC A series head - max effort circuit race
Replies: 17
Views: 953

Re: Pushing the limits of a BMC A series head - max effort circuit race

Can you lift the valve to .700in or more safely? I only know them and other similar BMC / BL style heads to take 0.625” or so. The valvetrains are wet noodles on all these engines. Small journals, missing a cam bearing for the oil pump / dist drive, long pushrods, and because of their displacement,...
by hoffman900
Fri Mar 08, 2024 3:59 pm
Forum: Engine Tech
Topic: Most aerodynamic Muscle Cars?
Replies: 69
Views: 6062

Re: Most aerodynamic Muscle Cars?

AC Cobra 67 Vette From personal experience, both of those had dangerous lift at speed. A family friend / mentor raced a 289 Cobra back in the day. Plenty of lap records, 2nd to a newer psuedo factory backed ‘69 Vette at the SCCA National Championship in 1970… they were bricks. Corvette was more sli...
by hoffman900
Fri Mar 08, 2024 11:15 am
Forum: Engine Tech
Topic: Pushing the limits of a BMC A series head - max effort circuit race
Replies: 17
Views: 953

Re: Pushing the limits of a BMC A series head - max effort circuit race

What are you expecting power wise out of that? Looks great! I know a builder who got similiar numbers out of those. Here is what it did with a camshaft Mike did for him, and fuel injected: DFFDBE05-32F4-4B9D-B134-9DCF7706F575.jpeg A handful of flowbench tests, including Longman and Swiftune heads: h...
by hoffman900
Sun Mar 03, 2024 10:37 am
Forum: Engine Tech
Topic: valve timing events??
Replies: 53
Views: 7290

Re: valve timing events??

The exhaust valve isn’t stopping the flow, rising cylinder pressure does. If you do it right, at peak power, the the port flow is nearly stopped by the time the exhaust valve closes. The port is already beginning to slow down before BDC. To quote the late MadBill from like 15-18 years ago, “if gass...
by hoffman900
Sun Mar 03, 2024 7:40 am
Forum: Engine Tech
Topic: valve timing events??
Replies: 53
Views: 7290

Re: valve timing events??

I'm referring to air/fuel movement established into the cylinder and the inertia it has, not the state of the inlet port at valve opening. Do you mean the Inertia from the accelerated fuel and air in the runner when the piston is reversing after BDC and the inlet valve is starting to close? Erland ...
by hoffman900
Sat Mar 02, 2024 7:21 pm
Forum: Engine Tech
Topic: valve timing events??
Replies: 53
Views: 7290

Re: valve timing events??

Honda measuring droplet size as it enters the cylinder. Measured vs simulation: Hondaincylinder.jpg Hondaincylinderagain.jpg Different port lengths and two different injector types (low pressure and high pressure). This is 20 year old stuff. They can do much better now. There is a lot to take away h...
by hoffman900
Sat Mar 02, 2024 7:11 pm
Forum: Engine Tech
Topic: valve timing events??
Replies: 53
Views: 7290

Re: valve timing events??

Here is a (lawnmower) carburetor at 28,546 fps:


You can see the fluid inertia keeps it flowing between pulses, but it's only being distributed when the intake valve is open.