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So these power caps really work then

1K views 27 replies 17 participants last post by  Trig 
#1 ·
Guy on strathy crooze selling his nova seem's to think so
220 bhp with a power cap and reprofiled cam's some guy
got a lift in it and it's rapid must be true then :rolleyes:

check it out

http://www.strathycruise.com/phpBB/viewtopic.php?t=12834

now where's pvd's number and get my power cap order now
before the rush start's
 
#8 ·
lol, dunno the guy to comment. Gotta say tho that surely if it was 220 and running throttle boddies it woulda been listed in the main stuff at the top, seeing he says all the important stuffs there.

15s 1/4 is really far too slow for that. Ross9 had a wee run in with a red turbo or t/b one the other week and it abused him, his cars not slow like, and it does 14.5.

We aint all bad on strathy tho mind ;)

Alan
 
#12 ·
This is what 250bhp looks like:

2092cc 16v C20XE DOHC. ITG air filter, Jenvey 48mm parallel throttle bodies, smoothed to the enlarged SBD inlet manifold and smoothed to the enlarged head. The head is extensively modified, ported and flowed in every way. The cams are Kent made SBD items. The inlet cam has an 11.2mm lift with 300 degrees duration. each cam is adjustable with vernier pulleys. The exhuast cam has 11.1mm lift and 295mm duration. The cams run on solid lifters opperating Paul Ivey high flow valves. The valve heads and valve seats have been modified with three and four angles respectively to further increase air flow into the engine. Valve guides have been upgraded to calisbro bronze ones. The valves are held by SBD double valve springs on sepecial valve seats. These are held in place by titanium valve spring caps. The injectors have been uprated to Pico high flow ones with a modified fuel rail and high spec FSE fuel pressure regulator with pressure gauge. The head is held to the block via a Cometic stainless steel head gasket. The pistons are 88m high compression Omega pistons held by shot peaned rods and ARP rod bolts. The crank case breather system has been modified to allow better movement of gas through the engine - this is vented off via a Piper-X crank case filter. Spark plugs are NGK-R connected to Bosch leads and fed by a late C20XE twin coil pack. The engine is running distributorless and is controled by an MBE 956 ECU with an SBD wiring loom. The exhaust manifold is a BTB made SBD item which is painted in high temp paint and wrapped. The system is 2.5" mild steel made by Maniflow. The backbox is stainless steel with Vectra GSi tailpipes. The oil pump pressure has been increased to hold around 65-70psi at about 3000rpm. Oil is Vauxhall 5W40 fully synthetic. The mechanical compression is about 12:1, the rev limit is at 8500rpm. Power is about 250bhp @ 8200rpm with around 190lb/ft @ 5500rpm.

I would guess that he has around 170bhp tops.
 
#16 ·
:eek: :confused: erm, i have a mantzel power cap on me manta, mainly cos the sfi box fouls on the bonnet.

is there a major hate of these items?

shud i remove it?

it seems to go a lot better with it on, cos i have an sfi box that has been trimmed and sealed to not foul the bonnet, seems a lot happier with the power cap on.

cheers,

mark.
 
#17 ·
16vmantamark said:
:eek: :confused: erm, i have a mantzel power cap on me manta, mainly cos the sfi box fouls on the bonnet.

is there a major hate of these items?

shud i remove it?

it seems to go a lot better with it on, cos i have an sfi box that has been trimmed and sealed to not foul the bonnet, seems a lot happier with the power cap on.

cheers,

mark.
the sfi was designed specifically to be its volume by Vauxhall to boost torque while the power crap does produce more power its only at the top end and up till then it loses out on power and torque to the sfi box so overall the car is slower even tho noise and feel make it seem quicker

you sure it fouls? Animals 16v Manta doesnt appear to have that problem..?
 
#20 ·
The following guide lines are for engine operating in the 5000-6000 rpm rage. V8's with one large plenum feeding all 8 cylinders does not work all that well as far as the Helmholtz resonator goes, but if this is the case, plenum volume should be about 40-50% of total cylinder displacement. For a four cylinder 50-60% works well. For 3 cylinders (6 cylinder engine with two plenums), each plenum needs to be about 65-80% of the 3 cylinders it feeds. If a boost is desired in a higher rpm range, closer 7000-7500 rpm, the plenum will need to be 10-15% smaller. To get a boost in the 2500-3500 rpm range, it will need to need about 30% larger
so that means the sfi would be about 1 litre capacity, making it smaller or making it not exist (ecotec adapter) would shift torque boost up the rev range, or negate it alltogether.
 
#22 ·
yeah thats what its called "helmholtz resonator"

The plenum size of a Helmholtz resonator may go against the typical plenum size rules, but the rules change when the resonator is being used. The whole Idea of a plenum is to allow the gases to slow down and gain density. The Helmholtz plenum on the other hand makes a dense charge by use of pressure waves, in the same way tuned port intake runners work. This helmholts plenum sizing method does not apply to engines that do not use a tuned intake pipe. Many engines simply have the air cleaner assembly directly on the carb or throttle body having very little intake length. In those cases the Helmholtz resonator system does not work
 
#26 ·
well mine defo seems quicker, shame it wasnt r/roaded b4 i changed it.

i see where you's are commin from like, makes sence.

with my xe in the manta the sfi box wud foul the bonnet, come to think of it, it did, nice dent. good job i got a nice 400 bonnet to go over winter.

think i also need some uprated engine mounts to stop the engine rocking as much, the power cap caught wen i hit the redline doin donuts the other day :eek:

at the end of the day, the car revs smoother, seems to pull better and to be honest, seems a touch better on petrol, we will find out what its like when i get it on the rollers.

cheers,

mark.
 
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