Effect gain with 2.9 inlet and cams on a 2.8?

[Danny Salling 0]

How much will i gain with those to parts? Some say that the inlet will not give any gains without the 2.9 throtlebody, but is that correct?

[rusty dan 1]

well, I think the 2.9 being 100cc more than the 2.8 is not going to give 16hp so I think the the TB and inlet manifold do a job to help breathing so I think thats where the increase helps.

[FishWick 21]

2.8 and 2.9 cams are identical.

The 2.9 has a higher rev limit though, and a higher flowing inlet manifold.

Throttle plate size on OBD1 2.8 and 2.9 is the same. 2.8 throttle has a ramp in it to speed up gas flow at low rpm and the 2.9 is the same bore all the way through, but has a dual stage opening mechanism to mimic the 2.8's ramp behaviour.

OBD2 throttle plate is the smallest and has the same inlet as the OBD1 2.8.

Many people prefer the torquier delivery of OBD2 with it's 'restricive' intake parts. I know I do :-)

[UnitedMotorsport 55]

Interestingly the 2.9 cams have a different part number to that of the 2.8 ones

2.9:

021 109 101M

021 109 102A

2.8:

021 109 101N

021 109 102B

Weather this means the specs of them is different I dont know, but I suspect they are.

Food for thought.

[sharky_70 0]

i know the only 2.9 OBD2 was on the syncro, but can the OBD1 2.9 inlet etc be modded to run on 2.8 OBD2?

[Danny Salling 0]

2.8 cams are 248* and 2.9 cams are 256*.

[Danny Salling 0]

2.8 OBD1 TB are 64mm and 2.9 TB is 72mm. The 2.8 OBD2 TB is (as far as i know) also 72mm.

[RIX 0]

obd1 tb´s are both 64,can be bored out to i think 66

obd2 is 72,not smaller then obd 1.

[Danny Salling 0]

My german is´nt that good but this is from an auktion on the german ebay:

VW VR6 2,9 Liter Drosselklappe

Grösserer Innendurchmesser im gegensatz zur 2,8 Liter Drosselklappe

optimal zur Leistungssteigerung

[FishWick 21]

I have 2.9, OBD1 2.8 and OBD2 throttles at home and the OBD2 is definitely the smallest. My OBD1 2,8 and 2.9 have the same size plate, so I don't know what throttles you got in Europe.

Didn't know that about the cams though, good to know for future reference!

[RIX 0]

we have talked about it before kev

i have a friend yhat had a 97 obd 2 vr6 and his was 72mm

[Danny Salling 0]

So bottomline is that there is no effect to gain with the 2.9 TB, it just works better in high revs than the 2.8 one, and the 2.8 one works better in low revs?

[Danny Salling 0]

Am i wrong?

[gavinvr6 0]

i dont no much about this type of this but if mild cams are 268 this makes em 20 degrees more/higher, however its done. so 2.9's being an extra 10 degree's 'ish' would make em slightly better than 2.8's in a 2.8

also the throttle body argument was had not to long ago, i have an obd1 coil pack engine, it has exactly the same throttle body as a corrado, when my original engine was swapped out i used a low milage obd2 and fitted my obd1 set up. the obd2 tb is much smaller than the obd1, by about 10mm. i know because i looked at them side by side when i was trying to smooth out the internals in both. the obd2 tb will almost fit inside an obd1 tb its that much smaller.