home news shop history forum membership galleries regions calendar contact
   

Go Back   106 Rallye Register Forum > TUNING, MODIFICATIONS & UPGRADES > Engine, Exhaust & Gearbox

Engine, Exhaust & Gearbox ECU chips, decats, cam kits,

Reply
 
Thread Tools Display Modes
Old 18-03-2019, 10:35 AM   #1
scagliettipl
REGISTERED FORUM USER - NON MEMBER
 
Join Date: Mar 2019
Location: Polska
Posts: 3
User Gallery
Advice needed Catcams 1321708 on C2 VTS, Please help

Hey Guys,
I had struggled with my car past year and made some modifications, those are:
Original complete TU5JP4S engine (bottom, pistons and head)
- Ashley 4-2-1 header + custom 2,25 inch complete exhaust
- Ported TU5JP4S head, just to remind :-)
- ACL crank bearings
- Ported orginal steel intake
- Ported and polished MK1 steel throttlebody
- and .... designed for TU5J4 type engine 13217708 cams
As all of you is aware that those cams do not cope with TU5JP4S head (valve to piston clearance) i want to stay with them fitted
So... my question to all of you is:
As i do not want to make any cutouts on pistons, what do you think if it would be wise to exchange headgasket (stock 0.6mm) to thicker one, i had search last two weeks for thicker counterpart, and i found Cometic MLS C4493-075 (79mm bore and 1.90mm thick one). Should it be enough to give more clearance between valve and piston at TDC? I know that it will affect compression ratio, could it be that it will fall drastically?
There are also other items availiable from them (ex 1.67,2.03, 2.18 mm)
Please advise how to deal with that issue budget wise as i had already spend much time and effort on that.
Last thing is that car is waiting in queue to be dyno'ed on standalone ECU, as soon as i will solve the case.
Please help me with that as you have much more experience

Best Regards
Norbert
Posted via Mobile Device
scagliettipl is offline   Reply With Quote
Old 28-03-2019, 10:22 AM   #2
drmo
106 RALLYE REGISTER MEMBER

 
drmo's Avatar
 
Join Date: Apr 2007
Location: Slovenia
Posts: 813
User Gallery
Stock engine has 11:1 compression ratio and uses 0,62mm head gasket. With 1,90mm head gasket it will bring the compression down to 9.6:1 which is to low. You could use a more cr (and also money) friendly 1,37mm gasket from a TU5JP engine, which will bring the compression down to about 10.1:1 (or there abouts), but I dont know if the difference of only 0,75mm will be enough to set cam timing properly with enough clearance.

The lower compression ratio will have a bad impact on the burn and thus will reduce the torque and responsiveness of the engine in the lower revs, and also have impact on all the rev range. With more agressive cams it will only be worse, as they have higher lifts at TDC which results in poorer performance in the lower revs, as the dynamic compression ratio is lower.
Not to mention that by using thicker head gasket, you will have poor squish area of the pistons, which will also make the burn less efficient, thus reducing power. That is also one of the things why high compression pistons are made.
If you must use stock pistons then the only proper way would be making cutouts in the stock pistons. It will make less impact on the compression ratio and will have better burn thus make more horse power. While your at it, you could also skim the head for 0,5mm and bring the compression back up. Valves are inclined so the skim of 0,5mm will not bring the valves 0,5mm closer to the pistons, but more like 0,4mm, which you can make deeper cutouts and still gain in compression by skimming.

This is a TU5JP4 piston (NOT JP4S), but should be very simmilar. The cutouts that I made were for 708s. We also skimmed the head 0,5mm to bring the compression up from 10.8:1 to 11.4:1 and with cutouts bring it down a little bit (probably around 11:1, didn't measure the cutouts):


You can also time the cams differently than catcams suggests, with less lift at TDC, but it will impact performance. If you are not willing to make cutouts, that is probably the best option.
__________________
my project thread:
-->Click!<--
drmo is offline   Reply With Quote
Old 28-03-2019, 01:30 PM   #3
welshpug
106 RALLYE REGISTER MEMBER

 
welshpug's Avatar
 
Join Date: Mar 2006
Location: cwmcarn
Posts: 4,920
User Gallery
just change the pistons, see if you can find C2R2 items, they give about 12-1 and plenty of valve clearance for a cam that gives 180 bhp on stock intake.
welshpug is offline   Reply With Quote
Old 29-03-2019, 11:05 AM   #4
drmo
106 RALLYE REGISTER MEMBER

 
drmo's Avatar
 
Join Date: Apr 2007
Location: Slovenia
Posts: 813
User Gallery
Quote:
Originally Posted by welshpug View Post
just change the pistons, see if you can find C2R2 items, they give about 12-1 and plenty of valve clearance for a cam that gives 180 bhp on stock intake.
C2R2 pistons are not direct fit. They require an overbore to 78.75mm. On top of that they are pricey (more then 1000 for a set).
The C2R2 cams were limited by the R2 class to 11mm lift and 280 duration. The timing is 5.1mm lift @ TDC (inlet) and 3mm @ TDC(exhaust) which is why they need such high compression and deep pocket pistons. Very harsh cam on the valvetrain also.
__________________
my project thread:
-->Click!<--
drmo is offline   Reply With Quote
Old 11-04-2019, 02:31 PM   #5
scagliettipl
REGISTERED FORUM USER - NON MEMBER
 
Join Date: Mar 2019
Location: Polska
Posts: 3
User Gallery
Thanks Guys, for all advices I'm selling them too much hassle for C2 TU5JP4S engine, they are on sales section if anyone care !
Posted via Mobile Device
scagliettipl is offline   Reply With Quote
Old 12-04-2019, 09:02 AM   #6
drmo
106 RALLYE REGISTER MEMBER

 
drmo's Avatar
 
Join Date: Apr 2007
Location: Slovenia
Posts: 813
User Gallery
Quote:
Originally Posted by scagliettipl View Post
Thanks Guys, for all advices I'm selling them too much hassle for C2 TU5JP4S engine, they are on sales section if anyone care !
Posted via Mobile Device
Actually it is quite the same hassle as fitting to TU5J4 engine, if you want to time them correctly and have the correct valve to piston clearance.
__________________
my project thread:
-->Click!<--
drmo is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT. The time now is 07:30 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.