P6 air filter dyno test

Penguin

Penguin

Active Member
this might interest a few of you, i have just run up a freshly rebuilt P6 V8 on the dyno. The engine was stock with the exception of a hurricane cam.

The interesting bit was the difference between a P6 and SD1 airfilter assembly and what happened when i put SD1 filters in the P6 airbox

 
Thems the big filters I am running - Ryco A1705 down here IIRC. I suspect a significant part of the gain is due to the SD1 air box's larger inlet hole. A bigger filter surface area (other things not changing) will always suffer a lower pressure drop IMHO.
 
jp928 said:
Thems the big filters I am running - Ryco A1705 down here IIRC. I suspect a significant part of the gain is due to the SD1 air box's larger inlet hole. A bigger filter surface area (other things not changing) will always suffer a lower pressure drop IMHO.
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i agree, at lower rpm the big filters in the P6 came close to the sd1 airbox, but at high(?) rpm the SD1 airbox really made a difference, 11bhp is a big gain when you only have 160 in the first place
 
Years ago autosport.com did some work on a Commodore to see how much output could be improved cheaply, easily. Result (roughly) - remove restrictions on air getting INTO the airbox by removing the production inlet trumpet and cutting a 100mm + hole in the case.
 
Penguin said:
i agree, at lower rpm the big filters in the P6 came close to the sd1 airbox, but at high(?) rpm the SD1 airbox really made a difference, 11bhp is a big gain when you only have 160 in the first place
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True but how many people drive at max revs flat out in a P6?:LOL::LOL::LOL::LOL:
 
keynsham1 said:
True but how many people drive at max revs flat out in a P6?:LOL::LOL::LOL::LOL:
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4 lbft torque at peak is worth having, but then again if your foot is not flat on the floor your never see it.

i must admit one of the reasons i rarely drive my own P6 is despite having only covered 40,000 miles it doesnt actually run/go that well, so i dont like driving it. Trouble is compared to my daily driver which is a 530 turbo diesel beemer everything feels gutless! At some point it wil get a larger capacity engine!
 
Penguin said:
4 lbft torque at peak is worth having, but then again if your foot is not flat on the floor your never see it.

i must admit one of the reasons i rarely drive my own P6 is despite having only covered 40,000 miles it doesnt actually run/go that well, so i dont like driving it. Trouble is compared to my daily driver which is a 530 turbo diesel beemer everything feels gutless! At some point it wil get a larger capacity engine!
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My daily outperforms Sparky in acceleration (13.2 quarter), top speed, lack of wind noise, handling, fuel consumption, ICE, etc, but it really doesn't have any soul. OK I know the Rover isn't alive, it does have the character not found in modern cars. I was out for a spin yesterday, and really must get out and about more often :)
 
Did anyone notice how much better the SD1 box sounded also? You talk about automatics well ANY power and especially torque helps.

When you only get 95bhp at the wheels and your losses remain pretty much the same, then 6bhp is noticeable. Cam, heads, filters can net you 20-25% on an auto... But true the exhaust manifolds are basically crap and are going to be your weak link in the chain when taking it further.

Did you ever do a back to back with P6s heads and a direct swap to 10bolt late ones? I'm led to believe these flow 16% better than the P5/P6 type and therefore there is absolutely no point doing anything with the originals and it's best to simply bin them and replace.
 
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Penguin said:
i agree, at lower rpm the big filters in the P6 came close to the sd1 airbox, but at high(?) rpm the SD1 airbox really made a difference, 11bhp is a big gain when you only have 160 in the first place
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You haven't got 160bhp to use - you'll see 135-140 of that at the wheels with a manual box, so that 11bhp is even more in proportion.
 
Hi, I do wonder about the power losses being up to 20 BHP which is about 15KW, that's a lot of heat to dissipate.

Colin
 
PeterZRH said:
You haven't got 160bhp to use - you'll see 135-140 of that at the wheels with a manual box, so that 11bhp is even more in proportion.
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thats a strange comment, i quote flywheel power like every single car manufacturer.

Plenty of car manufactures change engine spec and power by a lot less than 11 bhp. on the basis of what you said it was pointless Rover adopting bigger bore exhaust manifolds on an S or bigger bore systems on late autos
 
Penguin said:
thats a strange comment, i quote flywheel power like every single car manufacturer.

Plenty of car manufactures change engine spec and power by a lot less than 11 bhp. on the basis of what you said it was pointless Rover adopting bigger bore exhaust manifolds on an S or bigger bore systems on late autos
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Yes but we don't drive "at the flywheel". So with the losses broadly staying the same what you feel at the wheels is actually proportionally greater in percentage terms.
 
PeterZRH said:
Did you ever do a back to back with P6s heads and a direct swap to 10bolt late ones? I'm led to believe these flow 16% better than the P5/P6 type and therefore there is absolutely no point doing anything with the originals and it's best to simply bin them and replace.
Click to expand...

no i havnt. but i did run up another engine 3.5 engine on the same exhaust system, which used a similar cam, same Compression ratio, go fast filters in a P6 air box, with a lightly tickled intake manifold and mildly ported 4.6 heads, that engine made a couple of BHP more than this engine made on the sd1 airbox, so its fair to assume the 4.6 heads are worth a bit
 
PeterZRH said:
Yes but we don't drive "at the flywheel". So with the losses broadly staying the same what you feel at the wheels is actually proportionally greater in percentage terms.
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yes, no, maybe!

the thing is if you measure flywheel power you are dealing with far less variables
 
Penguin said:
no i havnt. but i did run up another engine 3.5 engine on the same exhaust system, which used a similar cam, same Compression ratio, go fast filters in a P6 air box, with a lightly tickled intake manifold and mildly ported 4.6 heads, that engine made a couple of BHP more than this engine made on the sd1 airbox, so its fair to assume the 4.6 heads are worth a bit
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Was that moving from SD1 heads to 10bolt heads or P6 type to 10bolt? I'm interested in the effect of the larger valves mostly. The 10bolt heads are only a minor improvement on the SD1 type from what I understand.
 
PeterZRH said:
Was that moving from SD1 heads to 10bolt heads or P6 type to 10bolt? I'm interested in the effect of the larger valves mostly. The 10bolt heads are only a minor improvement on the SD1 type from what I understand.
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the engine in this airbox test had SD1 heads, so the difference would be moving between SD1 heads and 10 bolt. i guess that could be another video sometime!

just to muddy the water more, i ran up a rebuilt but totally standard P6 engine, it didnt have the same top end urge, but noticeably better down torque and probably better for an auto unless you have lead boots
 
Would there be much difference if you ran the engine in a hot engine bay, rather than out of the car hence running on cooler air?
 
I find removing as much of the guide out of the inlet and exhaust ports gives greatest cheapest gains.
So shortened, tapered inlet guides, and shortened exhaust guides, waisted stem inlet valves, proper nice 3 angled seats with a bit of bowl work. angles on valves optimised. All of this makes very good gains, but not on P6 heads.
Having done both I would bypass the Hurricane, and start with the Typhoon.
At least 10.5:1

Not a good recipe for a lazy tourer though. Fast GT car, yes.
 
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