I intend to up the CR to around 11:1 with some forged pistons but the question i need answering is what some of cam profile am i ultimately looking for?
So i have a standard C20XE engine with a C30 Rotrex charger to add at some point next year
I intend to up the CR to around 11:1 with some forged pistons but the question i need answering is what some of cam profile am i ultimately looking
for?
You need to lower the c/r not raise it.
Inlet duration and valves can be reduced as the compressor will make up for this, and open up the exhaust.
Although to be honest just use the cars standard cams and buy a book to work out what to do with the cam timing.
Yep, do not increase compression to 11 to 1 with any sort of forced induction
You'll lunch the engine with detonation in seconds
My initial thoughts on CR has always been low as poss, loads of boost but the new way is to maintain a good CR and low boost as in the new OMEX/ROTREX
kit.
The zetec in JeffW's car runs 11.5:1 and is currently happy at 300hp(from memory).
LINKY
Its basically the same when peeps are adding turbos too these days.
Bailey Performance(Dan-very helpful chap) does the same. They say that the car behaves very well, with good throttle respone(on std CR) and no
horrible lag due to an inefficient low comp engine.
I'm only quoting what others tell me here so dont shoot the messenger please
It just seems a great plan so i'm going to give it a try!
Not wanting to hijack but i have a Turbo engine that I'm part way converting to Supercharged and I yet to investigate whether it would be better to use the Turbo cams or the NA cam for the engine.
quote:
Originally posted by liam.mccaffrey
Not wanting to hijack but i have a Turbo engine that I'm part way converting to Supercharged and I yet to investigate whether it would be better to use the Turbo cams or the NA cam for the engine.
quote:
Originally posted by Phil.J
quote:
Originally posted by liam.mccaffrey
trying to sort badly running turbo conversions can be soul destroying..
Tell me about it!
jeffw - 11/12/12 at 09:01 AMquote:
Originally posted by laptoprob
My initial thoughts on CR has always been low as poss, loads of boost but the new way is to maintain a good CR and low boost as in the new OMEX/ROTREX kit.
The zetec in JeffW's car runs 11.5:1 and is currently happy at 300hp(from memory).
LINKY
Its basically the same when peeps are adding turbos too these days.
Bailey Performance(Dan-very helpful chap) does the same. They say that the car behaves very well, with good throttle respone(on std CR) and no horrible lag due to an inefficient low comp engine.
I'm only quoting what others tell me here so dont shoot the messenger please
It just seems a great plan so i'm going to give it a try!
The C30-94 in my car only makes 15psi at 100K rpm (the 94 is limited to 100K the smaller ones are 120K). Of which I get about 9psi at the plenum. The engine is running forged pistons/rods (10.7:1 from memory so pretty much stock CR) and has ported/polished head with cams between Piper 285 and mild race. Car produces 300HP at the wheels...
BaileyPerformance - 11/12/12 at 11:25 AMquote:
Originally posted by snapper
Yep, do not increase compression to 11 to 1 with any sort of forced induction
You'll lunch the engine with detonation in seconds
That depends on the engine, the forced induction system and how well its tuned. High CR is more common on turbo / SC engines now, a turbo pinto would struggle at 11 to 1 CR but a XE/zetec/duratec would be fines long as its tuned properly (not with guess work!)
laptoprob - 12/12/12 at 08:56 PMquote:
Originally posted by BaileyPerformance
quote:
Originally posted by snapper
Yep, do not increase compression to 11 to 1 with any sort of forced induction
You'll lunch the engine with detonation in seconds
That depends on the engine, the forced induction system and how well its tuned. High CR is more common on turbo / SC engines now, a turbo pinto would struggle at 11 to 1 CR but a XE/zetec/duratec would be fines long as its tuned properly (not with guess work!)
HI Dan, knew you would be along anytime soon....
In your experiance on these setups am i btter off sticking with std cams and just trying verier pulleys?
My initial plan was to go for a flowed/ported head with some mediocre cams with a steadyish lift(286/11.5mm)?
laptoprob - 12/12/12 at 09:01 PMquote:
Originally posted by jeffw
The C30-94 in my car only makes 15psi at 100K rpm (the 94 is limited to 100K the smaller ones are 120K). Of which I get about 9psi at the plenum. The engine is running forged pistons/rods (10.7:1 from memory so pretty much stock CR) and has ported/polished head with cams between Piper 285 and mild race. Car produces 300HP at the wheels...
Spoke with Richard at TTS today who tells me that my C30-74 will happily put out 12 psi but the key is to make sure you keep as much as possible at the plenum by using a good cooler with little pressure drop.
I would be a happy chappy with 300hp at the wheels but i'm searching for that at the fly so think its quite achievable looking at what you have and also speaking with Dan@Bailey about his conversions.
Looking forward to the task in hand indeed....
laptoprob - 12/12/12 at 09:02 PMquote:
Originally posted by liam.mccaffrey
Not wanting to hijack but i have a Turbo engine that I'm part way converting to Supercharged and I yet to investigate whether it would be better to use the Turbo cams or the NA cam for the engine.
Which engine do you have?
jeffw - 12/12/12 at 09:51 PMCertainly with a decent cooler (air or water) mine would be well into the high 300s at the fly. Trouble is the gearbox/prop/English axle wouldn't stand it. Until I can afford the Sequential box & high-spec Atlas there is little point.
mark chandler - 12/12/12 at 10:36 PMYou may find 'special turbo cams' are just lower spec than standard for the engine.
I,m pretty sure when ford bought out the RS turbo, 1600cc engine the cam used was from a 1300 engine.
liam.mccaffrey - 13/12/12 at 12:04 AMIts a volvo T5, also available in NA trim.
quote:
Originally posted by laptoprob
quote:
Originally posted by liam.mccaffrey
Not wanting to hijack but i have a Turbo engine that I'm part way converting to Supercharged and I yet to investigate whether it would be better to use the Turbo cams or the NA cam for the engine.
Which engine do you have?
snapper - 13/12/12 at 06:45 AMI once talked to a tuner in Colchester who was struggling with a high compression radical cam engine that the owner bolted a turbo to
Undrivable the tuner said, it comes on cam just as the turbo boost hits, driving it meant that it just span up its wheels as soon as you hit 4kand went sideways
laptoprob - 13/12/12 at 06:59 PMquote:
Originally posted by snapper
I once talked to a tuner in Colchester who was struggling with a high compression radical cam engine that the owner bolted a turbo to
Undrivable the tuner said, it comes on cam just as the turbo boost hits, driving it meant that it just span up its wheels as soon as you hit 4kand went sideways
Hence the reason i went supercharger not turbo
jeffw - 13/12/12 at 08:08 PMMy power curve is virtualy a straight line. The more you rev it the more power you get, there is no sudden kick like a turbo.
Have a look at this video down the straights to see what I mean
This is with my son in the car and I was taking it easy but you can get a feel for the linear power delivery. Remember to switch to 1080p
[Edited on 13/12/12 by jeffw]
laptoprob - 13/12/12 at 08:42 PMquote:
Originally posted by jeffw
My power curve is virtualy a straight line. The more you rev it the more power you get, there is no sudden kick like a turbo.
Have a look at this video down the straights to see what I mean
This is with my son in the car and I was taking it easy but you can get a feel for the linear power delivery. Remember to switch to 1080p
[Edited on 13/12/12 by jeffw]
Love the soundtrack and the way the engine responds. Never loses that revability that the turbos suffer with which is what sells it to me.
Do you or have you had any trouble with overheating and where did you put the intercooler?
jeffw - 13/12/12 at 08:48 PMUsing a standard Polo rad without an issue (so far). The intercooler is in the nose of the car
laptoprob - 14/12/12 at 08:11 AMquote:
Originally posted by jeffw
Using a standard Polo rad without an issue (so far). The intercooler is in the nose of the car
Nice job Jeff, who did the pipes and intercooler?
BenB - 14/12/12 at 08:21 AMBack to the original question, you actually want quite a tame cam. Sporty cams generally have loads of overlap to encourage scavenging of the exhaust from the cylinders. In a forced induction setup you don't want oodles of overlap because you'll wee away all the PSI you've been lovingly creating.
Regarding compression ratios it all depends on what boost level you're using, what fuels you're going to run, what level of intercooling you're going to have, whether you'ld consider water or methanol injection etc etc.
You can run an engine on RON95 at 11:1 but you'ld be restricted on boost levels (prob high single figures) even if you run a goodly size intercooler.
In my photo archive there's a scan of graph from G.Bell's Forced Induction Tuning showing recommended boost vs CR.
jossey - 14/12/12 at 08:26 AMRob,
How am I supposed to keep up with you now.....
Right I need a hayabusa now.
Good luck with the project though.
Just a quick question.... Say you put the supercharger on and let's say it touches 320hp??? Ish... Then what's next?
jeffw - 14/12/12 at 09:25 AMThe intercooler is a Toyosport EBay special and the pipework was made up by Fury Sportscars when they did the install for me. It is very space limited at the front of a Phoenix hence why the oil cooler is in front of everything.
The max plenum temp I see after a 20min track session is 50 deg C which is OK. It does drop 6psi across the cooler though.
jeffw - 14/12/12 at 10:16 AMquote:
Originally posted by BenB
Back to the original question, you actually want quite a tame cam. Sporty cams generally have loads of overlap to encourage scavenging of the exhaust from the cylinders. In a forced induction setup you don't want oodles of overlap because you'll wee away all the PSI you've been lovingly creating.
Regarding compression ratios it all depends on what boost level you're using, what fuels you're going to run, what level of intercooling you're going to have, whether you'ld consider water or methanol injection etc etc.
You can run an engine on RON95 at 11:1 but you'ld be restricted on boost levels (prob high single figures) even if you run a goodly size intercooler.
In my photo archive there's a scan of graph from G.Bell's Forced Induction Tuning showing recommended boost vs CR.
These 'new-age' rotrex supercharged systems are effectively 'super' NA engines and the tuning is based on this idea. Low boost (1 bar in my case) and high compression, big cams etc.
BenB - 14/12/12 at 01:22 PMFair enough- although I don't see how the risk of detonation when you have boost and a high CR ration is fundamentally changed by the method you have created the boost!
From the sounds of it people have got these chargers to work with high CRs and rad cams- I just can't understand how...
JAG - 14/12/12 at 01:50 PMBen; fundamental physics/thermodynamics haven't changed.
The way I read this thread these guys have simply created a relatively tuned NA engine and then slapped on a 'charger (doesn't matter what type) and run it at low boost levels to avoid detonation.
Your comments about valve overlap, detonation and heat still apply to these engines. The method that has been used has simply changed the balance between power WITHOUT boost and power WITH boost.
On older boosted engine designs the engine-without-boost made less power and the boost was used to increase power.
On the new designs the engine-without-boost makes more of the overall power and the boost simply adds the last little bit.
By doing this I guess you can create an engine that behaves more like an NA engine whilst giving the specific power outputs associated with boosted engines.
jeffw - 14/12/12 at 01:54 PMExactly this. My cams are not big lift, somewhere between 285 Piper and mild race. They come in around 3k and are all over and done with at 7.3K. As the Rotrex is at max rpm at 7100rpm in my car this is ideal so there was no point in changing. Race cams wouldn't be any good but fast road/rally cams are fine.
Oddified - 14/12/12 at 04:59 PMquote:
Originally posted by jeffw Race cams wouldn't be any good but fast road/rally cams are fine.
Or dial some of the overlap out with the cam timing/vernier wheels.
Ian
laptoprob - 14/12/12 at 05:40 PMquote:
Originally posted by BenB
Back to the original question, you actually want quite a tame cam. Sporty cams generally have loads of overlap to encourage scavenging of the exhaust from the cylinders. In a forced induction setup you don't want oodles of overlap because you'll wee away all the PSI you've been lovingly creating.
Regarding compression ratios it all depends on what boost level you're using, what fuels you're going to run, what level of intercooling you're going to have, whether you'ld consider water or methanol injection etc etc.
You can run an engine on RON95 at 11:1 but you'ld be restricted on boost levels (prob high single figures) even if you run a goodly size intercooler.
In my photo archive there's a scan of graph from G.Bell's Forced Induction Tuning showing recommended boost vs CR.
Hi Ben, i had heard this before about the overlap but wondered if i can gain anything much by adding some lift etc.
Ill have alook at the graph, thanks for that.
jeffw - 14/12/12 at 07:15 PMAtspeed played with the verniers when they mapped the car and we saw a big jump in torque while moving the exhaust cam.
laptoprob - 14/12/12 at 09:42 PMquote:
Originally posted by jeffw
Atspeed played with the verniers when they mapped the car and we saw a big jump in torque while moving the exhaust cam.
I know that you can add an XE exhaust cam to a C20LET engine and swing the cam a few degrees and it gives big torque gains which sort of ties up with what Atspeed have done.
Maybe they dialled some overlap out and gained some boost back hence the torque?
Either way i,m going to go down the fast road cam route and do some work on the vernier pulleys once its on the rollers.
Thanks for your input fellas (especially Jeff,great inspiration). Watch this space.
laptoprob - 14/12/12 at 09:45 PMquote:
Originally posted by jossey
Rob,
How am I supposed to keep up with you now.....
Right I need a hayabusa now.
Good luck with the project though.
Just a quick question.... Say you put the supercharger on and let's say it touches 320hp??? Ish... Then what's next?
Haha, i reckon at Blyton power doesnt mean everything anyway. Its such a short circuit it really gets down to some good handling.
If i hit 320hp(which is doubtful) then i may need to go back to 2 wheels to quench my thirst.....if the wife allows it that is
jossey - 14/12/12 at 09:57 PMWell good luck with the winter upgrade. If I can get hold of a 3.38 diff then ill goto other tracks but currently the 3.92 n 3.62 are all I have an I lost the details for the guy who said he could change the pinions in the 3.62
Speak soon.
Ps I can't beat you on handling but mine is a little lighter than yours so maybe that will help ... In the dry
David
quote:
Originally posted by laptoprob
quote:
Originally posted by jossey
Rob,
How am I supposed to keep up with you now.....
Right I need a hayabusa now.
I
Good luck with the project though.
Just a quick question.... Say you put the supercharger on and let's say it touches 320hp??? Ish... Then what's next?
Haha, i reckon at Blyton power doesnt mean everything anyway. Its such a short circuit it really gets down to some good handling.
If i hit 320hp(which is doubtful) then i may need to go back to 2 wheels to quench my thirst.....if the wife allows it that is
Craigorypeck - 18/12/12 at 10:26 PMI'm running 11:1cr with newman fast road cams very modest 6psi but it goes well. dialled out some overlap and got a bit more boost.
found this useful. ezinearticles.com/?Supercharger-Tuning-Through-Cam-Selection-and-Cam-Timing&id=2473412
laptoprob - 21/12/12 at 08:08 AMquote:
Originally posted by Craigorypeck
I'm running 11:1cr with newman fast road cams very modest 6psi but it goes well. dialled out some overlap and got a bit more boost.
found this useful. ezinearticles.com/?Supercharger-Tuning-Through-Cam-Selection-and-Cam-Timing&id=2473412
Cheers for the link, very informative. What did your engine do on the dyno? And its a Zetec i take it? Any other head mods?
Craigorypeck - 21/12/12 at 03:48 PMNot dynod yet.. running in new block atm.
Yb engine with ported head.