Speed-Talk is running on www.Speed-Talk.com

IMPORTANT: Update your bookmarks to https://www.speed-talk.com/forum/
(Right-click the URL and select "Bookmark this link")

Search found 2594 matches

by ptuomov
Sat Sep 24, 2022 11:32 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

“ approximately 1.3mm quench clearance.” 75E05FF7-BD28-4588-B29F-EF619028BD47.jpeg B7826A3D-7B78-4F20-AB9A-B04B76133CFA.png This engine has basically zero squish but a lot of tumble with intake port angle normal to the exhaust valve and no piston crown, tumble which will be well broken down to small...
by ptuomov
Fri Sep 23, 2022 7:00 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

"The incoming mixture speed is around 0.2-0.6 Mach, where peak is around peak valve lift. That means a lot of TKE potential lays in the incoming impulse. Therefore intake runner, port and valve seat design have a huge effect on what is coming as well as valve timing (reverse flow). To preserve this ...
by ptuomov
Thu Sep 22, 2022 8:35 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Bigchief632 wrote: Thu Sep 22, 2022 8:27 am So have we figured out how much it affects power yet? 13 pages, no definitive number, just a bunch of theory and I thinks and it seemed to helps.
On what kind of engine? 2-valve wedge at 6000rpm or 4-valve pent roof at 11000 rpm?
by ptuomov
Wed Sep 21, 2022 9:39 pm
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Porsche 4-valve turbo engines, AMG/MB M139 2L turbo, Koenigsegg V8, etc. I believe they have spherical dish pistons with a band that’s not matched with the head to produce squish. But they of course do break up the tumble into smaller turbulent eddies as the combustion chamber gets compact with the...
by ptuomov
Wed Sep 21, 2022 1:30 pm
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Finnish the most popular racing class in its competive form, Lancia Fiat TC engine is still number one. Folkrace is also a class where the rules are open i should say, so that reason i wont call it a piece of s*** "hemi". I know only little about quench, or mixture motion things, so that historical...
by ptuomov
Wed Sep 21, 2022 11:34 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

I know by far not all engines in essential racing series in Europe, but spherical heads are very rarely used in the late 90'ies till today. Hemi-heads are much more popular in the US, maybe they survived longer there. What I know is that flat head, wedged heads and roof chamber heads are used today...
by ptuomov
Wed Sep 21, 2022 8:57 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Even without a clearly defined squish pad (as in a hemi), piston motion still creates significant charge motion. As the piston moves upward on the compression stroke, it scrapes the air (and fuel) from the cylinder wall. Where does this air go and at what velocity? All the squish calculations (incl...
by ptuomov
Tue Sep 20, 2022 7:58 pm
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Porsche 4-valve turbo engines, AMG/MB M139 2L turbo, Koenigsegg V8, etc. I believe they have spherical dish pistons with a band that’s not matched with the head to produce squish. But they of course do break up the tumble into smaller turbulent eddies as the combustion chamber gets compact with the ...
by ptuomov
Tue Sep 20, 2022 11:10 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

The moving charge that fills the cylinder has some amount of kinetic energy in it. The way I've understood it from reading large eddy simulation results is that tumble is useful in preserving that kinetic energy until near the TDC where it can then be broken into the kind of turbulence that is usefu...
by ptuomov
Tue Sep 20, 2022 8:56 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

I don't think one can infer much anything about the squish height during the combustion TDC from the piston to head clearance during overlap TDC. Inferring the squish height at combustion TDC from piston to head clearance at overlap TDC will give you the wrong squish height and consequently the wro...
by ptuomov
Tue Sep 20, 2022 7:43 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Just an example of Larry Widmer's B20-300 whp attempt engine, the squish height was according his post 0.81 mm cold and got zero'd at 9500 rpm. That fits quite well to my assumptions, as the B20 has a unfortunate rod-stroke ratio of 1.57:1 at a 28 mm compression height, causing a bit higher mechani...
by ptuomov
Mon Sep 19, 2022 8:57 pm
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 217
Views: 5873

Re: Does quench affect power?

Sorry for interrupting the actual discussion, but I wanted to add my two cents here. I calculate squish height at the applicated engine speed range and engine temperature, means elongation of the crank drive due to thermal expansion and by acceleration. On a 86 mm stroke one should consider 0.55 mm...
by ptuomov
Mon Sep 19, 2022 3:24 pm
Forum: Engine Tech
Topic: Porsche 993 twin turbo
Replies: 112
Views: 3232

Re: Porsche 993 twin turbo

You are re-inventing a wheel. You need to contact RS-Tuning (in Germany), get upgraded turbos as they’d recommend and cams. And you need a bigger intercooler. Exhaust is a waste of money, you will result in 540 hp. This setup is equal to RS-Tuning Turbo S upgrade, same as Gemballa. RS-Tuning has th...
by ptuomov
Thu Sep 15, 2022 5:48 pm
Forum: Engine Tech
Topic: NA DOHC Camshaft recommendation
Replies: 22
Views: 941

Re: NA DOHC Camshaft recommendation

BLSTIC wrote: Thu Sep 15, 2022 2:47 pm Locked as in you don't hand the adjustable gears available and have locked the factory continuously variable items to be fixed, or you do have adjustable ones and just can't vary the timing with the engine running?
Great question.
by ptuomov
Thu Sep 15, 2022 8:24 am
Forum: Engine Tech
Topic: NA DOHC Camshaft recommendation
Replies: 22
Views: 941

Re: NA DOHC Camshaft recommendation

Unfortunately the cams are locked, intake is at 105, ex 108. Adjusting the cams does the usual of what to expect, eg advance retard. If you have to buy new cams for each lobe separation angle, then I’d seriously consider inputting the engine into Vannik’s engmod4t software. That would allow you to ...