inlet/exhaust manifolds

Spammer Joined: 27 Jul 2004 Posts: 5717

now on my black rt 1.8 SPI ,the manifolds were on top of eachother ,in fact they were touching eachother which was heating the inlet manifold up making me think also heating the air going in as well causing performance decrease Rolling Eyes

1-does this cause a lot of loss in performance ???

2-does this work the same way in all sohc engines due to valves being run by 1 cam ????

Forum Moderator Joined: 18 Feb 2004 Posts: 7432

1 - no, there was none there to begin with Laughing

2 - No, you can still have a crossflow design with a single cam

Spammer Joined: 27 Jul 2004 Posts: 5717

excellent

so what if the f3p SPI or MPI engine was a cross flow ,would it push more power than it is at the moment ??????

Site Subscriber Joined: 07 Oct 2004 Posts: 2281

I imagine you'd see a slight increase, mainly due to the improvement in gas flow (?)

Spammer Joined: 27 Jul 2004 Posts: 5717

on the same issue i found this on internet ,which i think can be quite valuable wrapped around the exhaust manifold especially on the 16v

SILICAFLEXâ„¢ TAPE AB
Heat Resistant Tape

Silicaflex Tape AB features all the characteristics of Silicaflex blanket and sleeve, but is supplied in a tape form for the convenient wrapping of hoses, cables and pipe.

Coated on one side with a pressure sensitive adhesive backing that facilitates ease of installation, Silicaflex Tape AB is a convenient, field installable high temperature tape solution to high temperature problems. The pressure sensitive adhesive decomposes at high temperatures, leaving a perfectly installed, tape wrapped hose, cable or pipe.

Like all Silicaflex products, Silicaflex Tape AB will withstand 1800Â°F (982Â°C) continuous and short term exposure up to 3000Ã¸F (1650Â°C).

Silicaflex Tape AB is supplied in widths 2" (50 mm) and 4" (102 mm)

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

1. Yes, every 4 degrees temp goes up you get around a decrease of 1% in power.

2. Like Neal said.

If it was a crossflow design then yes it would have a lot more power, it would have canted valves thus a better combustion chamber and improved flow due to less shrouding. And the inlet ports wouldn't be as hot. If ti was a good head then it would probably be faster point to point than the 16V due to more torque but a bit less top end power.

Don't wrap a cast iron manifold, it would be ok on the steel downpipe but wrapping cast parts can make em crack.

Spammer Joined: 27 Jul 2004 Posts: 5717

cheers chris ,
interesting stuff really ,i wonder why renault did not make it a crossflow than ,were they not aware at the time they designed the engine ??? or is it to do with fuel economy rather than the performance ???

Forum Moderator Joined: 02 Mar 2004 Posts: 19978

fuel economy goes up with power to an extent as you reduce the BSFC for a given output, increase the efficiency and you reduce the waste.

basically if it burns properly, less petrol goes out the exhaust (HC's) you gain the power that would have otherwise gone out the exhaust.

Black smoke is power thats not been used!

Theres lots of factors in it but thats the basics of it.

non crossflow design was probably for packaging more than anything else.

It also simplifies the valve train layout.

Spammer Joined: 27 Jul 2004 Posts: 5717

so what other renault engines are crossflow design ????
are there any 8 valves ??????

also how hard would it be to convert a f3p head into a cross flow???

Site Subscriber Joined: 07 Oct 2004 Posts: 2281

Energy engines are 8v and cross-flow.

As for F3P cross-flow conversion well you'd need to relocate inlet/exhaust ports on opposite sides so you'd need a new cylinder head designing and manufacturing at a foundry.

Not cheap and I doubt it's something any of them would want to do as a 'one-off'. There would certainly be more cost effective methods of upping the power.

Spammer Joined: 27 Jul 2004 Posts: 5717

bollocks ,thats why the 1.4 energy engine can give you 80bhp when a feckin 1.8 SPI can only give 95

what were they thinking ffs Question