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Old 9 Sep 2021, 08:32 (Ref:4072744)   #991
Casper
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Casper should be qualifying in the top 5 on the gridCasper should be qualifying in the top 5 on the grid
Very few people realise the differences between a two valve motor and the 4 valve motor because it is rarely spoken about. Down low the two valve motor will stomp on any 4 valve of the same capacity (NA) but if the upper rpm limit is too low then the 4 valve loses out because it performs better at higher RPM. That MB and Nissan motors never worked properly in SC is not surprising given they were handicapped from day one by the 4 valve configuration.
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Old 11 Sep 2021, 00:54 (Ref:4073002)   #992
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Originally Posted by Casper View Post
Very few people realise the differences between a two valve motor and the 4 valve motor because it is rarely spoken about. Down low the two valve motor will stomp on any 4 valve of the same capacity (NA) but if the upper rpm limit is too low then the 4 valve loses out because it performs better at higher RPM. That MB and Nissan motors never worked properly in SC is not surprising given they were handicapped from day one by the 4 valve configuration.
Yep, plus the benefit of only one camshaft mounted low in the engine for the pushrod engines, whereas the 4 valve DOHC engines have 4 camshafts, so four times the weight, mounted up high - so heavier and a higher centre of gravity.

Pushrod engines may well be considered "old" (although overhead cam engines aren't much younger) but there are ARE some benefits, particular when there is a set of regulations containing rev limits to manage costs.
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Old 12 Sep 2021, 18:37 (Ref:4073397)   #993
V8 Fireworks
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Originally Posted by Casper View Post
Very few people realise the differences between a two valve motor and the 4 valve motor because it is rarely spoken about. Down low the two valve motor will stomp on any 4 valve of the same capacity (NA) but if the upper rpm limit is too low then the 4 valve loses out because it performs better at higher RPM. That MB and Nissan motors never worked properly in SC is not surprising given they were handicapped from day one by the 4 valve configuration.
Is that 100% true in all cases? So a 1995 Corolla 16-valve 1.6L would have less low down torque than a 1995 VW-Golf 8 valve 1.6L?

It seems curious that almost all economy car engines -- including General Motors' own normally aspirated four cylinders -- would bother with a more expensive 16 valve layout if it didn't bring any significant benefits, even in low rpm tractability which is important in an economy car.

There are some engines like the VW 4-cylinder, the VW VR6, and the Alfa Romeo Busso V6, which came with both 2-valve per cylinder and later 4-valve per cylinder versions, so it would be curious to compare dyno plots for the two layouts.

Here's one:

8V VW GTI, tuned


16V VW GTI, tuned


It would seem the 15% loss in low rpm torque is worth the peak power being 15% superior. To compare engines of the same era, I'd guess you'd need to put a 16V Toyota 4AGE car on the dyno on the same day as the 8V VW GTI, to compare low rpm torque of the two 1.6L motors and observe the difference of two layouts between competitor engines.

[PS. Why aren't we racing interesting cars like Golfs and Corollas in the ATCC again? https://www.youtube.com/watch?v=ebNBhr2ZWNE Their omission is most curious!]

Last edited by V8 Fireworks; 12 Sep 2021 at 19:07.
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Old 12 Sep 2021, 19:13 (Ref:4073412)   #994
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The 8-valve GTI engine seems to produce anywhere from 7-8 more hp all the way up to ~5700rpm, where it finally gets overtaken by the 16-valve GTI engine. The latter is very superior to the 8-valve between 5700rpm and 7000rpm, which undoubtedly reflects why most racing categories e.g., Formula One, LMP, MotoGP, prefer 4-valve or 5-valve (where permitted) 4-stroke piston engine layouts.

However, the 4-valve Supercars runners always had the option of fitting smaller valves (& smaller ports) to improve torque and increase port velocity, and in Todd Kelly's series on designing their Ford racing engine he seemed to give the impression that Kelly Racing had designed their 2-valve combustion chamber to fit the biggest valves they could, likewise he gave the impression they had opened the ports up a lot too. So that seems curious.

Last edited by V8 Fireworks; 12 Sep 2021 at 19:21.
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Old 13 Sep 2021, 04:56 (Ref:4073537)   #995
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Mixer should be qualifying in the top 3 on the gridMixer should be qualifying in the top 3 on the gridMixer should be qualifying in the top 3 on the gridMixer should be qualifying in the top 3 on the grid
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Is that 100% true in all cases? So a 1995 Corolla 16-valve 1.6L would have less low down torque than a 1995 VW-Golf 8 valve 1.6L?
You literally undermine any argument you make after this... Toyota are famous for making the most woefully torqueless engines, basically wishing to put motorcycle characteristics into their road cars due to heads designed by.... Yamaha

Toyotas VVTi engines, without a turbo, can't suck the skin off a custard.
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Old 14 Sep 2021, 05:43 (Ref:4073769)   #996
leothedrummer
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But they aren't turbo fours against normally aspirated V8"s. You are dreaming if you think that can work.
You were saying?



This kind of regressive thinking is a cancer. What's the point on doing anything (as a series) if there's a steadfast belief that there are no other possible options to explore?
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Old 14 Sep 2021, 23:47 (Ref:4073962)   #997
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Casper should be qualifying in the top 5 on the gridCasper should be qualifying in the top 5 on the grid
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This kind of regressive thinking is a cancer. What's the point on doing anything (as a series) if there's a steadfast belief that there are no other possible options to explore?
There are plenty of options out there but very few want to change from the status quo. Class racing used to be the only racing and allowed a whole field to mix it up but that seems to be banned now for some reason.
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Old 15 Sep 2021, 03:03 (Ref:4073985)   #998
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There are plenty of options out there but very few want to change from the status quo. Class racing used to be the only racing and allowed a whole field to mix it up but that seems to be banned now for some reason.
I think sadly the issue with class racing now has become one of the class cars not being much less costly to run with the downside that TV cameras focus on the outright battles more than the class runners.... therefore class cars running round at the back get limited TV (ie sponsor) exposure. So bottom line = harder to get sponsors on the basis of lack of TV exposure.

That is my understanding anyway.
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Old 15 Sep 2021, 05:32 (Ref:4073998)   #999
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I think sadly the issue with class racing now has become one of the class cars not being much less costly to run with the downside that TV cameras focus on the outright battles more than the class runners.... therefore class cars running round at the back get limited TV (ie sponsor) exposure. So bottom line = harder to get sponsors on the basis of lack of TV exposure.

That is my understanding anyway.
Class racing if done well is great for the teams, sponsors and fans. Have a look at IMSA where they have very fast (and relatively expensive) in the same race as GT3 cars which are relatively more affordable. It is great racing from a spectators perspective of watching the faster cars negotiate the slower cars. The lower class cars get their own TV because they are having their own battles, as well as when the fast cars have to overtake.

You cant tell me that BJR and Kelly Grove are happy about the TV coverage they get when running around the back half of the field?
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Old 15 Sep 2021, 11:25 (Ref:4074059)   #1000
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one five five should be qualifying in the top 10 on the gridone five five should be qualifying in the top 10 on the grid
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I think sadly the issue with class racing now has become one of the class cars not being much less costly to run with the downside that TV cameras focus on the outright battles more than the class runners.... therefore class cars running round at the back get limited TV (ie sponsor) exposure. So bottom line = harder to get sponsors on the basis of lack of TV exposure.

That is my understanding anyway.
Class racing has been THE selling point of Le Mans since 2000, and its subservient series.
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Old 16 Sep 2021, 03:07 (Ref:4074164)   #1001
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sizzle should be qualifying in the top 5 on the gridsizzle should be qualifying in the top 5 on the grid
Happy to bag the hell out of Roland on one hand but still gives him money to run Brock with the other.

I find it hard to argue about rethinking Gen 3 though.

https://www.speedcafe.com/2021/09/16...ted-gen3-over/
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