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 65 matches

by LotusElise
Fri Sep 30, 2022 11:06 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 262
Views: 7505

Re: Does quench affect power?

Do they sell matching modern pistons for those aftermarket heads? All of the “old one” web site pistons look like they are artifacts from some archaeological dig from the previous millennium. To be diplomatic, those companies who bought Larry's heads and design and it's production work on different...
by LotusElise
Fri Sep 30, 2022 10:01 am
Forum: Engine Tech
Topic: Does quench affect power?
Replies: 262
Views: 7505

Re: Does quench affect power?

Here is a prtsc about interference between R19 and experimental stuff.. Its a pain for me, but i can do roughly something using cars own system. I didn't check or optimize ignition advance with respect to crank position, so that table doesnt have much value for this topic.. Now for a comparison oth...
by LotusElise
Fri Sep 30, 2022 9:02 am
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

Yeea, i may like the hole process too much. :oops: If it fit the purpose, way not. We all like to work on that stuff, it is part of it. How knows the optimum if not experienced the non-optimum? A fast way to optimum causes somewhere else some effort. My first NA engine exceeding the 130 Nm/Liter bo...
by LotusElise
Fri Sep 30, 2022 7:50 am
Forum: Engine Tech
Topic: Camshaft lobe design by Billy Godbold
Replies: 48
Views: 1770

Re: Camshaft lobe design by Billy Godbold

I picked some alloy and my collaugue helped measuring the conductivity. Very nice :). You call yourself a hobbyist? That is top level hobbyist which is not achieved by quite a few professional. I've done this for my doctoral thesis, measuring and validating heat fluxes to calculate heat transfer co...
by LotusElise
Fri Sep 30, 2022 7:14 am
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

Static flow: Area which has lowest static pressure, but dynamically area which has highest pressure. Its not all about changes in walls, it comes to how that area is utilized by the flow, so pulsed flow and NA vs boosted make also a difference? Just thinking. That's an interesting point. Pulsed flo...
by LotusElise
Fri Sep 30, 2022 6:39 am
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

Like I've said before.... how do you define... what the throat is? What part is the throat in this illustration? https://www.thesamba.com/vw/gallery/pix/2054896.jpg Throat is the smallest cross section of the flow path, it defines to a major part how much oxygen can pass per stroke and it is, in mo...
by LotusElise
Fri Sep 30, 2022 4:53 am
Forum: Engine Tech
Topic: Camshaft lobe design by Billy Godbold
Replies: 48
Views: 1770

Re: Camshaft lobe design by Billy Godbold

I dont understand why we have plastic hammers in my daily job. I often take a copper one, and i hold it from end of the stem. My colleagues think im nut. The Copper-Berilium valve seat do not only have a great heat transfer coefficient material-wise but also have better valve bounce calm property t...
by LotusElise
Fri Sep 30, 2022 3:53 am
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

The takeaway was that unless your 400cc bike was making more than 150hp your ports were probably too big Yeap. I have a nice example for that too. One of my Kiwi well known guys built a 2-Liter-V8-NA-engine, based on a Synergy V8 engine (Hayabusa heads, custom block and stuff) which put 460 hp@14,6...
by LotusElise
Thu Sep 29, 2022 3:17 pm
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

Yes my local machine shop uses Mira seat cutting tool (that fancy model press button to concentrate). Here we are talking 5 or 4 valve engines, but my hats off for those 2 valve iron dukes who get it work! The 2-valve heads have an advantage on combustion, especially the low inclined angle wedge he...
by LotusElise
Thu Sep 29, 2022 3:07 pm
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

My rally car has 2 x 34.5 intake valves and i was thinking reverse flow when i did this chamber work. I also installed a complex 4-2-1 header design with chokes fitted every Y -junction starting from "junction of" cylinder head flange and headers. It remains to be seen.. So far i know it idles real...
by LotusElise
Thu Sep 29, 2022 2:56 pm
Forum: General Tech
Topic: Alternator for racing?
Replies: 10
Views: 207

Re: Alternator for racing?

At a punt I'd say maybe an old ext fan type, the characteristics look similar to a Bosch N1, either 14v or 28v, but maybe not, most curves are much of a muchness, unless you're squeezing a quart out of a pint pot I can't say by heart, I would have to check in the SAP data base. I was developing an ...
by LotusElise
Thu Sep 29, 2022 10:39 am
Forum: Engine Tech
Topic: Venturi Port by David Vizard
Replies: 28
Views: 1050

Re: Venturi Port by David Vizard

Got my hands on top notch engine, which was build into new block, new everything (Renault F4R it was) I cut that cylinder head into pieces... Now other part of the story is when my trusted machinist redid a valve job for my junk engine. He used a Mira and nice single angle blade. Btw this happened,...
by LotusElise
Thu Sep 29, 2022 6:47 am
Forum: General Tech
Topic: Alternator for racing?
Replies: 10
Views: 207

Re: Alternator for racing?

Just dug this up for anyone who might be interested ...... Thanks for sharing. What alternator is this specifically? I am really curious now... I was thinking of a 1.5:1 belt ratio in a 10,000 rpm engine of an alternator with 18,000 rpm maximum shaft speed. At 15,000 rpm the efficiency was around 3...
by LotusElise
Thu Sep 29, 2022 6:30 am
Forum: Offtopic Forum
Topic: How far a moderator of Don Terrils Speed talk can go?
Replies: 2
Views: 107

How far a moderator of Don Terrils Speed talk can go?

Hello guys, I am new to the board and I am really happy about the density of engine enthusiasts and specialists of different fields. I had already very helpfully discussions here, which inspired me. Yesterday I came across a thread in the David Vizard forum called "Jon Schmidt Video cam rebuff" by D...
by LotusElise
Thu Sep 29, 2022 5:18 am
Forum: General Tech
Topic: Alternator for racing?
Replies: 10
Views: 207

Re: Alternator for racing?

Typically alternators have an efficiency of 40% - 45% over much of their operating range ...... they generally get less efficient as rotational speed rises I've worked in alternator projects at an well known Stuttgart located company :wink: and from that I would always overdesign it because the eff...