stock cams

[dainys]

hello,
how many HP it is possible to have using stock cams (k26/27, RS2 EM, big IC, 76mm exhaust, injektors).
Thanks

[Jamo]

The cams won't be the limitation in that setup. Your turbo will define the max HP dependant on the size of the hotside ( exhaust ) of the turbo.

[Faheemo]

Stock Cams wont help the engine breed in the higer RPM's.
try a 7a exhaust cam, more lift, more hp in high rpms.

[S4turbo]

I know of engines with more than 500 hp, with original cams and unported top. With a gt3040 turbo. Not optimal setup though, rather late spool up.

J

[Jamo]

Stock Cams wont help the engine breed in the higer RPM's.
try a 7a exhaust cam, more lift, more hp in high rpms.

Yeh but you lose low end torque, You can do it but it wont hurt the total BHP output if you stick to original cams.

[Audi_CQ]

Yeh but you lose low end torque, You can do it but it wont hurt the total BHP output if you stick to original cams.

Why would you lose low end torque? 7A ex. cam has same timing as org. ex cam.
7A intake is another matter since it got more duration.

[20Vcqdriver]

timing

7A exhaust is not the same as 3b. 7A closes some 6degrees later and has a few more mm of lift. Not sure why it should affect low end torque, but you will have to have a re-chip to get the additional fuelling it will require at higher rpm.

[Audi_CQ]

7A exhaust is not the same as 3b. 7A closes some 6degrees later and has a few more mm of lift. Not sure why it should affect low end torque, but you will have to have a re-chip to get the additional fuelling it will require at higher rpm.

No. It's got the same timing.
Yes it has 2mm more lift, but that doesn't create overlap.
Do a quick search on the forum: "7A cam timing"

Why a fuel remap The maf sensor should do just fine.......

[Flat on my back]

Ex 7A vs 3B

http://www.s2forum.com/forum/showthread.php?t=22712

Is the data in the last post correct? Or we need an edit?

[20Vcqdriver]

Data

Carl is correct the 3B ex closes at 9deg before TDC whereas the 7A closes later at 3 deg before TDC and has more lift hence why the standard map will be wrong and the engine run lean at higher rpm, not something the MAF can automatically compensate for.

[Audi_CQ]

http://www.s2forum.com/forum/showthread.php?t=22712

Is the data in the last post correct? Or we need an edit?

Need an edit i think:

http://www.not2fast.com/audi/info/20_cams_1.xls

http://www.not2fast.com/audi/info/20_cams_2.xls

From factory manuals according to writer. In 20_cams_2.xls look at sheet "cams" and part nr is included.

[Audi_CQ]

Carl is correct the 3B ex closes at 9deg before TDC whereas the 7A closes later at 3 deg before TDC and has more lift hence why the standard map will be wrong and the engine run lean at higher rpm, not something the MAF can automatically compensate for.

Why should it run lean?
Think about how the MAF works: It meassures air flow and then fuel is added according to Mass Air Flow. A MAF is the perfect way to compensate for changes in airflow
Even if the 7A ex cam was some degrees different, intake airflow wouldn't change much. Most of the gain is in reduced pumping loss

[20Vcqdriver]

timing

Another source that agrees the timing is different (http://www.humanspeakers.com/audi/engines.htm)
Due to the change in overlap the maf will get slightly different signals hence leaning, not a problem during cruising as Lambda keeps mixture at AFR 14.7. If the only difference was lift then the MAF would indeed compensate as you stated.

[Audi_CQ]

Another source that agrees the timing is different (http://www.humanspeakers.com/audi/engines.htm)
Due to the change in overlap the maf will get slightly different signals hence leaning, not a problem during cruising as Lambda keeps mixture at AFR 14.7. If the only difference was lift then the MAF would indeed compensate as you stated.

As usual: if you want to be sure, don't trust anything you read and do it yourself
I've measured open: 42 before BDC, close 2 before TDC(picture is not from 7A cam timing, but results are ) so you're right about timing

About MAF: How would overlap make a change to a sensor sitting in front of the turbo? Sure you're not thinking about a MAP-sensor?