Vtec's compression ratio!!!

Shan2nu · 7th May 2005, 13:33

There seems to be some confusion regarding the Vtec's compression ratio. While the magazines claim it to be 9:1, the car manual says that the 9:0 compression ratio is for all OHCs except the Vtec model. The Vtec model seems to have a comp ratio of 9.6:1.

But yeah, the Vtec does suffer when run on 97 octane so, my guess is that it might infact be 9.6:1 and not 9:1 as claimed by the magazines.

Any views on this, Vtec owners?

Shan2nu

adya33 · 7th May 2005, 14:01

hey I am not a VTEC owner
but found this webpage over the internet which may be of your help

http://www.csgnetwork.com/compcalc.html

Rtech · 7th May 2005, 14:17

The comp ratio of the Vtec is 9.1:1

Mpower · 7th May 2005, 20:01

9.6 is most likely for international markets. Anybody know what the engine code for the VTEC. Was it D15Z or D15B.

The other difference between Indian and Malaysian VTECs could be the ignition timing. Indian version could have retarded timing to survive the low octane fuel.

Shan2nu · 7th May 2005, 20:48

Well, the Vtec here, has a B15 C2 engine.

Here's what the car manual has to say.........

Compression Ratio :
1.3 ltr engine -
8.8:1 (*2),
9.1:1 (*3)

1.5 ltr engine
9.4:1
9.0:1 (*4) - except Vtec
9.6:1 - Vtec

*1 - VTI, VTI-S, VL and VX models
*2 - India and Pakistan models
*3 - Except for India and Pakistan models
*4 - india, Indonesia and Philippine models.

So, it means that the 1.3 engine here has a 8.8:1 ratio, 9.0:1 for the 1.5s except the Vtec and the Vtec is 9.6:1.

Shan2nu

Rtech · 7th May 2005, 21:01

The Indian Vtec is 9.1:1

Shan2nu · 7th May 2005, 21:25

Quote:

The Indian Vtec is 9.1:1

Where'd you get that info from? And why isn't it mentioned in the manual?

Shan2nu

Rtech · 7th May 2005, 21:31

Maybe the manual states the figures for the engine tuned for other countries. My info is straight from Honda itself - the Vtec Homologation book. Doesn't get more accurate than that.

Revvmaster · 7th May 2005, 23:07

Quote:

Originally Posted by Rtech

Maybe the manual states the figures for the engine tuned for other countries. My info is straight from Honda itself - the Vtec Homologation book. Doesn't get more accurate than that.

I'd rather hold what Rtech is saying considering his work background.

Revv

7th May 2005, 13:33	#1
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 125 Times View My Garage	Vtec's compression ratio!!! There seems to be some confusion regarding the Vtec's compression ratio. While the magazines claim it to be 9:1, the car manual says that the 9:0 compression ratio is for all OHCs except the Vtec model. The Vtec model seems to have a comp ratio of 9.6:1. But yeah, the Vtec does suffer when run on 97 octane so, my guess is that it might infact be 9.6:1 and not 9:1 as claimed by the magazines. Any views on this, Vtec owners? Shan2nu
	() Thanks

7th May 2005, 14:01	#2
adya33 Senior - BHPian Join Date: Apr 2005 Location: Pune Posts: 1,839 Thanked: 183 Times	hey I am not a VTEC owner but found this webpage over the internet which may be of your help http://www.csgnetwork.com/compcalc.html
	() Thanks

7th May 2005, 14:17	#3
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	The comp ratio of the Vtec is 9.1:1
	() Thanks

7th May 2005, 20:01	#4
Mpower Senior - BHPian Join Date: Mar 2005 Location: Bangalore Posts: 10,409 Thanked: 1,730 Times View My Garage	9.6 is most likely for international markets. Anybody know what the engine code for the VTEC. Was it D15Z or D15B. The other difference between Indian and Malaysian VTECs could be the ignition timing. Indian version could have retarded timing to survive the low octane fuel.
	() Thanks

7th May 2005, 20:48	#5
Shan2nu Senior - BHPian Join Date: Feb 2004 Location: Hubli - Karnata Posts: 5,533 Thanked: 125 Times View My Garage	Well, the Vtec here, has a B15 C2 engine. Here's what the car manual has to say......... Compression Ratio : 1.3 ltr engine - 8.8:1 (2), 9.1:1 (3) 1.5 ltr engine 9.4:1 9.0:1 (4) - except Vtec 9.6:1 - Vtec 1 - VTI, VTI-S, VL and VX models 2 - India and Pakistan models 3 - Except for India and Pakistan models 4 - india, Indonesia and Philippine models. So, it means that the 1.3 engine here has a 8.8:1 ratio, 9.0:1 for the 1.5s except the Vtec and the Vtec is 9.6:1. Shan2nu Last edited by Shan2nu : 7th May 2005 at 20:52.*
	() Thanks

7th May 2005, 21:01	#6
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	The Indian Vtec is 9.1:1
	() Thanks

7th May 2005, 21:31	#8
Rtech Team-BHP Support Join Date: Apr 2004 Location: Bombay Posts: 5,770 Thanked: 359 Times View My Garage	Maybe the manual states the figures for the engine tuned for other countries. My info is straight from Honda itself - the Vtec Homologation book. Doesn't get more accurate than that.
	() Thanks