81 replies to this topic

[speedster]

A set of Shrek ([color=rgb(51,51,51);font-family:'Helvetica Neue', Helvetica, Arial, sans-serif;font-size:12px;]Schrick[/color]) cams maybe. Thorney seems to believe in them.

[Boombang]

It's irrelevant what they are or who rates them, it's mainly about their duration and timing that impacts CR. That then gets considered with all other components of the engine, which have been carefully picked on intended usage and required lifespan. This is why people pay a lot of money to have pro's build engines.

[speedster]

ok so we know we can run the engine with a higher compression ratio, with the help of pistons and cams. How do i think like a pro and find the optimal combination for an engine breathing through ITBs?

[Winstar]

A set of Shrek ([color=rgb(51,51,51);][font="'Helvetica Neue', Helvetica, Arial, sans-serif;"]Schrick[/color][/font]) cams maybe. Thorney seems to believe in them.

That's probably a reason not to use them, Stg 3 comp cams are proven to produce power at high revs.

I'd say a big key to what you can run is the quality of the ECU and it's control or the engine as that's what allows modern OEM engines to run such high compression ratios

[2-20]

ok so we know we can run the engine with a higher compression ratio, with the help of pistons and cams. How do i think like a pro and find the optimal combination for an engine breathing through ITBs?

 

http://www.wallacera.../dynamic-cr.php

 

http://www.hotrod.co...op_compression/

[Sticky]

A set of Shrek ([font="'Helvetica Neue', Helvetica, Arial, sans-serif;color:rgb(51,51,51);font-size:12px;"]Schrick[/font]) cams maybe. Thorney seems to believe in them.

Nooooooooooooo.

 

All show and no go IMHO

[Winstar]

ok so we know we can run the engine with a higher compression ratio, with the help of pistons and cams. How do i think like a pro and find the optimal combination for an engine breathing through ITBs?

 
http://www.wallacera.../dynamic-cr.php
 
http://www.hotrod.co...op_compression/

or if you really want to get into it there is a single cylinder freeware version or Lotus Engine Simulation http://www.lotuscars...eering-software

[oakmere]

The Schrick cams are good and give a 10 - 15 bhp gain. They work very well with the standard or 2.4 manifold and give a very good torque spread across the rev range. If you are looking at ITB's though you can use more extreme cams to lift max power into the 7-8000 rpm range.

[speedster]

 

A set of Shrek ([font="'Helvetica Neue', Helvetica, Arial, sans-serif;color:rgb(51,51,51);"]Schrick[/font]) cams maybe. Thorney seems to believe in them.

Nooooooooooooo.

 

All show and no go IMHO

 

From experience? What engine configuration?

 

The Schrick cams are good and give a 10 - 15 bhp gain. They work very well with the standard or 2.4 manifold and give a very good torque spread across the rev range.
If you are looking at ITB's though you can use more extreme cams to lift max power into the 7-8000 rpm range.

You reckon they are adding magic all the way to 8000RPM?

[Sticky]

 

A set of Shrek ([color=rgb(51,51,51);]Schrick[/color]) cams maybe. Thorney seems to believe in them.

Nooooooooooooo.
 
All show and no go IMHO
 

From experience? What engine configuration?
 

The Schrick cams are good and give a 10 - 15 bhp gain. They work very well with the standard or 2.4 manifold and give a very good torque spread across the rev range.
If you are looking at ITB's though you can use more extreme cams to lift max power into the 7-8000 rpm range.

You reckon they are adding magic all the way to 8000RPM?

I have them in my Vocky rebuilt iTB engine. She has all the usual mods: 11:1 cr, gas flowed head, balancer delete, full Tullett etc.

The dyno results compared to Fab and Vocky who have Comp cams are disappointing for both torque and power.There is a triple overlay print out somewhere

[speedster]

 

 

 

A set of Shrek ([color=rgb(51,51,51);][font="'Helvetica Neue';"]Schrick[/color][/font]) cams maybe. Thorney seems to believe in them.

Nooooooooooooo.
 
All show and no go IMHO
 

From experience? What engine configuration?
 

The Schrick cams are good and give a 10 - 15 bhp gain. They work very well with the standard or 2.4 manifold and give a very good torque spread across the rev range.
If you are looking at ITB's though you can use more extreme cams to lift max power into the 7-8000 rpm range.

You reckon they are adding magic all the way to 8000RPM?

I have them in my Vocky rebuilt iTB engine. She has all the usual mods: 11:1 cr, gas flowed head, balancer delete, full Tullett etc.

The dyno results compared to Fab and Vocky who have Comp cams are disappointing for both torque and power.There is a triple overlay print out somewhere

 

it was definitely the cams causing the disappointment? Did you replace them with another brand and profile and see any difference?

[speedster]

How does this look?

 

With Individual Throttle Bodies and engine running with a compression ratio of 12:1

 

Cams 

Intake - 280°@11.2

Exhaust - 280°@11.2

Standard Springs (SAAB Head) - OK with a rev limit of 8000RPM?

 

 

[techieboy]

Can't comment on the rest of it but doubt very much the valve springs are up to that rev limit without valve float/bounce. 7,250rpm is about the safe limit on the standard springs with the standard cams, let alone with anything high lift and steep ramp angles.

[Sticky]

 

 

 

 

A set of Shrek ([color=rgb(51,51,51);][font="'Helvetica Neue';"]Schrick[/color][/font]) cams maybe. Thorney seems to believe in them.

Nooooooooooooo.
 
All show and no go IMHO
 

From experience? What engine configuration?
 

The Schrick cams are good and give a 10 - 15 bhp gain. They work very well with the standard or 2.4 manifold and give a very good torque spread across the rev range.
If you are looking at ITB's though you can use more extreme cams to lift max power into the 7-8000 rpm range.

You reckon they are adding magic all the way to 8000RPM?

I have them in my Vocky rebuilt iTB engine. She has all the usual mods: 11:1 cr, gas flowed head, balancer delete, full Tullett etc.

The dyno results compared to Fab and Vocky who have Comp cams are disappointing for both torque and power.There is a triple overlay print out somewhere

 

it was definitely the cams causing the disappointment? Did you replace them with another brand and profile and see any difference?

 

Fab has essentially the same engine as me except for the cams so that is my conclusion.

 

Can't afford to change the cams to check myself.

[oakmere]

Sticky Your graph is so much smoother than fans though! Fab also has 1mm over sized and waisted stem valves as well. But I agree with you one big advantage of the ITB's is the ability to use wilder cams. I think the Schrick cams are a very good road cam for this engine though.

[Sticky]

Sticky Your graph is so much smoother than fans though! Fab also has 1mm over sized and waisted stem valves as well. But I agree with you one big advantage of the ITB's is the ability to use wilder cams. I think the Schrick cams are a very good road cam for this engine though.

I use my car for trackdays

 

Anybody want a set of Schrick cams  ?

[Arno]

But I agree with you one big advantage of the ITB's is the ability to use wilder cams.

 

Let's turn that around.. ITB's are usually needed (and bring advantages) when cam profiles become too wild to let them run on a single throttle body plenum setup.

 

Always found it a bit odd that the ITB development on the Z22 was historically a bit 'reversed' it seems..

 

What I mean to say is.. On many engines people start tuning them, porting heads, and fitting progressively wilder and wilder cams.

 

At a certain point the cams start to produce so many (reverse) pulses in the intake manifold plenum that they cause starvation of the other cylinders and it becomes very hard to let them idle (or you have to raise it to 1500-2000rpm) and the throttle response and general behaviour of the engine is such that it becomes a pig to drive (eg. kangarooing all over the shop)

 

That's the point when ITB's are usually fitted to engines.. (or twin webers in the 'olden days' )

 

With good mapping, a cylinder head that can support it and an engine that's set up for it an ITB equipped car can have silly duration and high lift cams in it and still idle almost as stock but rev to silly speeds (eg. a 2.0L 86x86mm version to 8000+). Or use a stroker engine and use the added displacement to get the same air velocities at a lower max rpm.

 

On the Z22 the initial reason for the ITB development seems to have been mostly 'the noise' I guess.. That's fine but a bit pointless from a performance viewpoint..

 

On the other hand, I guess it does mean that current Z22 or B207 N/A builds probably haven't reached the peak power the engine can produce by a long shot and much can still be gained/done.

 

Personally I like high-revving N/A engines..

 

Bye, Arno.

[oakmere]

300 bhp N/A in the build book. High compression ITB's and wild cams.

[oakmere]

I would love to get a decent single TB plenium on my car but lack of space means it my end up giving less performance as a road car. Any on in Europe running the Dbilas manifold with the OBD tuner?

[speedster]

I would love to get a decent single TB plenium on my car but lack of space means it my end up giving less performance as a road car. Any on in Europe running the Dbilas manifold with the OBD tuner?

I've been running a Dbilas + a 68mm TB with an Apexi SAFC. The SAFC can compensate and I can get correct fueling up till about 6400 after which the AFR goes lean, meaning I really need adjustment on the fueling side (the SAFC alters the ECU's air flow/pressure signal). Some suggest changing to LSJ injectors. Still not a 100% solution, the SAFC is more of a hack than a proper tune. I use an Innovate LM-1 Wideband Digital Air/Fuel Kit to monitor and help tune the burn.

 

The OBD tuner should certainly work well and it what I be looking at if I wasn't doing an ITB build.

Edited by speedster, 05 July 2013 - 01:36 PM.