Saxperience - Citroen Saxo Forum - View Single Post - JP's 220+bhp NA 16v Mango Westcoast

Sandy309 · 7th September 2012, 06:16

Cheers Scottie!

I'm not sure it's easy to make fair comparisons between an engine like this and boosted ones. The delivery is completely different and although in a straight line ultimately the boosted ones should be more powerful and hence quicker; around a track things are very different.
I've developed this spec through racing and it's been proven to be quicker than vastly more powerful charged cars running under the same rules. The elastic and bump delivery of a charged engine is not that helpful in FWD, especially out of tight corners, where traction dictates the speed onto the next straight, track position for defending and so on. It's a bit like filling a cup from a tap compared to a bucket! Having incisive, accurate and predictable driveability, with a wide power band to ride out a single gear on the exit from lower revs; really helps with track performance. That's why I've developed my engines towards a wide/full curve and nicely sloped part throttle behaviour. It's a happy side effect that it makes for a nice engine on the road too!
Spiky or stepped delivery can make the power seem greater, because of the calm and storm effect, but it's misleading in regard of true performance. It's a widely held view, that Honda deliberately dialled in the step in VTEC delivery to emphasise the higher rev performance, I've mapped alot of Honda engines and they all lose the step easily if you move the switching point!

Outline spec (SB= Sandy Brown and CS= Colin Satchell):

JP4 block over-bored to piston spec.
Standard 82mm JP4 crank, journals polished and balanced, SB/CS custom steel flywheel, CS front mounted crank trigger and alloy pulleys
SB custom H-section rods by Robson
SB custom slipper forged pistons by CP
Peugeot Sport baffle kit in J4 sump pan
SB race JP4 cylinder head (Serdi precision cut seats, ported to suit spec, surface ground gasket face)
SB custom single piece stainless valves
Piper double springs and modified Piper retainers
SB custom solid followers
SB custom cam profiles ground by Piper
Piper cam pulleys
SB and CS race spec GSXR1000 TB inlet (ported with the head) with twin injectors per cylinder and ITG filter
SB designed custom exhaust manifold, made by Edwards Motorsport
DTA S40 ECU on SB custom loom
Helix 7.25" race cerametallic paddle clutch
Built and mapped by SB

7th September 2012, 06:16	#1504
Sandy309 Regular Poster Join Date: Jan 2010 Location: Cornwall Posts: 349 Car(s): 106 XSi	Cheers Scottie! I'm not sure it's easy to make fair comparisons between an engine like this and boosted ones. The delivery is completely different and although in a straight line ultimately the boosted ones should be more powerful and hence quicker; around a track things are very different. I've developed this spec through racing and it's been proven to be quicker than vastly more powerful charged cars running under the same rules. The elastic and bump delivery of a charged engine is not that helpful in FWD, especially out of tight corners, where traction dictates the speed onto the next straight, track position for defending and so on. It's a bit like filling a cup from a tap compared to a bucket! Having incisive, accurate and predictable driveability, with a wide power band to ride out a single gear on the exit from lower revs; really helps with track performance. That's why I've developed my engines towards a wide/full curve and nicely sloped part throttle behaviour. It's a happy side effect that it makes for a nice engine on the road too! Spiky or stepped delivery can make the power seem greater, because of the calm and storm effect, but it's misleading in regard of true performance. It's a widely held view, that Honda deliberately dialled in the step in VTEC delivery to emphasise the higher rev performance, I've mapped alot of Honda engines and they all lose the step easily if you move the switching point! Outline spec (SB= Sandy Brown and CS= Colin Satchell): JP4 block over-bored to piston spec. Standard 82mm JP4 crank, journals polished and balanced, SB/CS custom steel flywheel, CS front mounted crank trigger and alloy pulleys SB custom H-section rods by Robson SB custom slipper forged pistons by CP Peugeot Sport baffle kit in J4 sump pan SB race JP4 cylinder head (Serdi precision cut seats, ported to suit spec, surface ground gasket face) SB custom single piece stainless valves Piper double springs and modified Piper retainers SB custom solid followers SB custom cam profiles ground by Piper Piper cam pulleys SB and CS race spec GSXR1000 TB inlet (ported with the head) with twin injectors per cylinder and ITG filter SB designed custom exhaust manifold, made by Edwards Motorsport DTA S40 ECU on SB custom loom Helix 7.25" race cerametallic paddle clutch Built and mapped by SB Last edited by Sandy309; 7th September 2012 at 07:41.