Re: Compression ratio of X-flow head on JH block?? (Shaggy)
8.26:1 with stock thickness head gasket
8.26:1 with stock thickness head gasket
Compression ratio of X-flow head on JH block??
As it says in the topic.. I need to know what the compression ratio of a JH block and X-flow head would be (with which headgasket)?
I'm tossing around the idea of building a 1.8 xflow turbo motor..
I'm tossing around the idea of building a 1.8 xflow turbo motor..
1 - 20 of 24 Posts
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
That's pretty exact, how did you come up with that?
That's pretty exact, how did you come up with that?
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
That's based on a head chamber volume of the JH of 30cc and 32cc for the X-flow head along with the CR of 8.5:1 for the stock JH
That's based on a head chamber volume of the JH of 30cc and 32cc for the X-flow head along with the CR of 8.5:1 for the stock JH
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
Thanks for the reply.. I guess it would be best to use the metal ABA gasket in this situation then right?
Thanks for the reply.. I guess it would be best to use the metal ABA gasket in this situation then right?
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
So what causes the subtle difference between the two in voloume when they "appear" to be the same? The valves are the same aren't they?
Maybe more head deck surface thickness for strength?
So what causes the subtle difference between the two in voloume when they "appear" to be the same? The valves are the same aren't they?
Maybe more head deck surface thickness for strength?
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
I think the difference is because the engine is 10% bigger so they made the chambers bigger too, I'm not sure but I think the 1.6L heads have smaller chambers (28cc?) than the 1.8L's too. IIRC the valve head size is the same but the X-flow have 7mm valve stems and they are shorter due to the hydraulic lifter. I think all the other 8v heads have 8mm valve stems.
I think the difference is because the engine is 10% bigger so they made the chambers bigger too, I'm not sure but I think the 1.6L heads have smaller chambers (28cc?) than the 1.8L's too. IIRC the valve head size is the same but the X-flow have 7mm valve stems and they are shorter due to the hydraulic lifter. I think all the other 8v heads have 8mm valve stems.
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
I mentioned the valves becuase if they were a differnt size or the seats were at a different height in the combustion chamber they would affect the volume and thus the compression ratio. It's possible that they made the combustion chamber wide around the outside of the valves to improve flow since the piston bore is larger. The stock head gasket is about 83mm across in diameter and the earlier solid lifter and hydro heads on the 1.8's are about 81mm across, so maybe they widened them.
I mentioned the valves becuase if they were a differnt size or the seats were at a different height in the combustion chamber they would affect the volume and thus the compression ratio. It's possible that they made the combustion chamber wide around the outside of the valves to improve flow since the piston bore is larger. The stock head gasket is about 83mm across in diameter and the earlier solid lifter and hydro heads on the 1.8's are about 81mm across, so maybe they widened them.
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
I didn't have a close enough look at my cross-flow head while it was still in my posession to really answer those questions. I cc'd the head to help me make more accurate CR calculations for the JH head-ABA block set-up I ended up using. I might soon have another opportunity to do a careful comparison if I do, I'll let you know what I find.
I didn't have a close enough look at my cross-flow head while it was still in my posession to really answer those questions. I cc'd the head to help me make more accurate CR calculations for the JH head-ABA block set-up I ended up using. I might soon have another opportunity to do a careful comparison if I do, I'll let you know what I find.
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
Ya, I'm very interested in the idea of using a crossflow on my 3A in a stock CIS car. No wiring or computer mods necessary. Just use an insert in the head for the stock injectors and move then around to the front. Sure the later injectors would work better with the computer but I would want it to be simple and cost effective. I'm sure someone must have done this but haven't heard about it yet. It would open up a lot of possibilities for people to put crossflows in early cars without much work. Then they would become hard to find for sure.
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Ya, I'm very interested in the idea of using a crossflow on my 3A in a stock CIS car. No wiring or computer mods necessary. Just use an insert in the head for the stock injectors and move then around to the front. Sure the later injectors would work better with the computer but I would want it to be simple and cost effective. I'm sure someone must have done this but haven't heard about it yet. It would open up a lot of possibilities for people to put crossflows in early cars without much work. Then they would become hard to find for sure.
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
I would like to do the same thing but possibly run dual carbs. If not carbs would the CIS-E be easy? Thats what I have in mind first off to save on money. Doesn't the X-flow flow much much better?
Thanx,
I would like to do the same thing but possibly run dual carbs. If not carbs would the CIS-E be easy? Thats what I have in mind first off to save on money. Doesn't the X-flow flow much much better?
Thanx,
Re: Compression ratio of X-flow head on JH block?? (JusAnothaRabbitRacer)
Well you could run carbs if you like, but the CIS is more efficient.
I'm presently talking with my head builder about retro fitting the CIS injectors, shouldn't be a problem, just needs an insert so the old injectors fit.
Yes the crossflow flows better then a stock old style 8V head but if it's well the old head could equal it. BUt the reason I want it is becuase the intake is one the front of the head and has steeper ports, the way it should be. No hot intake ports, more power right.
Well you could run carbs if you like, but the CIS is more efficient.
I'm presently talking with my head builder about retro fitting the CIS injectors, shouldn't be a problem, just needs an insert so the old injectors fit.
Yes the crossflow flows better then a stock old style 8V head but if it's well the old head could equal it. BUt the reason I want it is becuase the intake is one the front of the head and has steeper ports, the way it should be. No hot intake ports, more power right.
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
True..would u have to run your old CIS Intake Mani or can u run the crossflow one? Because if u run the old one will it clear the hood u think? Because if I could do a cost effective crossflow head vs. a ported CIS head then I may go through with it. Keep posting your findings.
Thanx,
True..would u have to run your old CIS Intake Mani or can u run the crossflow one? Because if u run the old one will it clear the hood u think? Because if I could do a cost effective crossflow head vs. a ported CIS head then I may go through with it. Keep posting your findings.
Thanx,
Re: Compression ratio of X-flow head on JH block?? (JusAnothaRabbitRacer)
You know that's so funny cuz I never even thought about what intake to use. I guess the best and simplest choice would be the stock crossflow intake, get it with the head. But what TB is used on a crossflow intake?
You know that's so funny cuz I never even thought about what intake to use. I guess the best and simplest choice would be the stock crossflow intake, get it with the head. But what TB is used on a crossflow intake?
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
I'm pretty sure the stock cis injectors/lines won't fit underneath the complete crossflow intake and the throttle body would end up on the passenger side of the car.. too far from the CIS air box. I'm going to try and fabricate a custom intake running off the front of the head and place the throttle body on the drivers side near the fuel distributor, which will also come in handy as the intercooler piping (for my turbo application) can be kept short and to the point..
I'm pretty sure the stock cis injectors/lines won't fit underneath the complete crossflow intake and the throttle body would end up on the passenger side of the car.. too far from the CIS air box. I'm going to try and fabricate a custom intake running off the front of the head and place the throttle body on the drivers side near the fuel distributor, which will also come in handy as the intercooler piping (for my turbo application) can be kept short and to the point..
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
You can't use the CIS manifold, at least not without modifying it, the port shape, bolt spacing and maybe port spacings as well are all different. The throttle body on the x-flow manifold faces the passenger side of the car and it's a single plate, I've never measured it but I'd guess its about 55mm or so and it has no idle adjustment screw.
You can't use the CIS manifold, at least not without modifying it, the port shape, bolt spacing and maybe port spacings as well are all different. The throttle body on the x-flow manifold faces the passenger side of the car and it's a single plate, I've never measured it but I'd guess its about 55mm or so and it has no idle adjustment screw.
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
Can someone please post a pic of a crossflow engine with a stock intake manifold, I need to see this puppy.
Thanx.
Can someone please post a pic of a crossflow engine with a stock intake manifold, I need to see this puppy.
Thanx.
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
There a picture on my website.
There a picture on my website.
Re: Compression ratio of X-flow head on JH block?? (ABA Scirocco)
Oh, that's a good site, thanx. I was hoping to see a pic of the intake from above so I can see what would be involved in welding a throttle plate to the drivers side and covering the original one. Maybe it's not possible but I need to see it from that angle to tell.
Oh, that's a good site, thanx. I was hoping to see a pic of the intake from above so I can see what would be involved in welding a throttle plate to the drivers side and covering the original one. Maybe it's not possible but I need to see it from that angle to tell.
Re: Compression ratio of X-flow head on JH block?? (A1Rocco)
James, I think that's quite doable, probably the best thing to do would be to cut off the whole plenum and construct a new one. I've still got the intake manifold at home, I'll take a closer look at it tomorrow afternoon and let you know.
James, I think that's quite doable, probably the best thing to do would be to cut off the whole plenum and construct a new one. I've still got the intake manifold at home, I'll take a closer look at it tomorrow afternoon and let you know.
1 - 20 of 24 Posts
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