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Bermoco
Samba Member
Joined: September 02, 2014
Posts: 75
Location: United States
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 Posted: Sat Jan 14, 2017 9:27 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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Thank you for your response Mr. Greenwood. I have read several of your posts and learn a lot of good information from them. Too high of a compression ratio makes sense.
For economic sake I will tear down the engine to see what is salvageable. Might be best to stick with 1700. |
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broomhandle
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Joined: August 04, 2009
Posts: 122
Location: Half Moon Bay, Ca
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| Posted: Tue Jan 17, 2017 1:38 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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| raygreenwood wrote: |
| Bermoco wrote: |
Great post and responses. I too have 3 motor cores. Two 1700 porsche motors with heads and a 2.0 bus engine. Also have an extra 2.0 crank and rods. Would like to know if rebuilding the 1700 case using 2.0 crank and rods with new 2056 pistons and liners, could the 1700 heads be used if they check out ok and flycut for the bigger liners? Trying to keep the build as reasonable as possible.
This will be for a dune buggy that weighs less than 1400 lbs. I too am in the Bay Area. We should compare notes.
Thanks |
The 2.0 crank and rods....no problem as the cases are qll essentially the same.
While the 1.7L heads...especially the "Q" series part # prefix are about the toughest out of all the stock heads......the problem with cutting them for 2.0 is that it so greatly enlarges the already large quench area in the 1.7L head......at the same tim3 mqking an qlready smalllish chqmber even smaller.....that your compression with be waaaay too high.
Likely above 10.0:1 if memory serves.....and there is no place in that head to remove enough material to bring compression down.
What you could do...cant remember the size off hand but it's right at 1.9 something liters....is build it with a 90mm piston, custom cylinders spacers, 71mm stroke and 1.7 heads.
I have heard of a couple....have no idea how they run.
That being said.....only the 1.7L heads need to be bored to take 2.0 cylinders. The 1.8 heads are the same size, roughly similar combustion chamber shape, same valve size....different plug and port angle.
The fastest cheapest way to make a decent 2.0 is with 1.8 heads. Ray |
My biggest issue is the heads.... my 411 case is the cleanest, and i was thinking fixing the 1.8 heads and run 2.0 pistons, or larger...
I always thought the 2.0 and 1.8 used different pistons, which made the heads different. but if you are saying the 1.8 can take 96mm pistons...
and what about the 2.0 bus heads? how are they different from the 1.8 heads? |
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raygreenwood
Samba Member
Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Jan 17, 2017 5:10 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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| broomhandle wrote: |
| raygreenwood wrote: |
| Bermoco wrote: |
Great post and responses. I too have 3 motor cores. Two 1700 porsche motors with heads and a 2.0 bus engine. Also have an extra 2.0 crank and rods. Would like to know if rebuilding the 1700 case using 2.0 crank and rods with new 2056 pistons and liners, could the 1700 heads be used if they check out ok and flycut for the bigger liners? Trying to keep the build as reasonable as possible.
This will be for a dune buggy that weighs less than 1400 lbs. I too am in the Bay Area. We should compare notes.
Thanks |
The 2.0 crank and rods....no problem as the cases are qll essentially the same.
While the 1.7L heads...especially the "Q" series part # prefix are about the toughest out of all the stock heads......the problem with cutting them for 2.0 is that it so greatly enlarges the already large quench area in the 1.7L head......at the same tim3 mqking an qlready smalllish chqmber even smaller.....that your compression with be waaaay too high.
Likely above 10.0:1 if memory serves.....and there is no place in that head to remove enough material to bring compression down.
What you could do...cant remember the size off hand but it's right at 1.9 something liters....is build it with a 90mm piston, custom cylinders spacers, 71mm stroke and 1.7 heads.
I have heard of a couple....have no idea how they run.
That being said.....only the 1.7L heads need to be bored to take 2.0 cylinders. The 1.8 heads are the same size, roughly similar combustion chamber shape, same valve size....different plug and port angle.
The fastest cheapest way to make a decent 2.0 is with 1.8 heads. Ray |
My biggest issue is the heads.... my 411 case is the cleanest, and i was thinking fixing the 1.8 heads and run 2.0 pistons, or larger...
I always thought the 2.0 and 1.8 used different pistons, which made the heads different. but if you are saying the 1.8 can take 96mm pistons...
and what about the 2.0 bus heads? how are they different from the 1.8 heads? |
I will have to check my books when I get back home....but IIRC...the 1.8 has 93mm pistons....and a 66mm stroke. The 2.0 should be a 94mm piston and a 71mm stroke with shorter rods.
From memory.....the 94 has a thinner cylinder wall so the head registers should be the same. If not....just spend a few bucks....not much...and have the 1.8s flycut to make the bore the same. Ray |
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Bermoco
Samba Member
Joined: September 02, 2014
Posts: 75
Location: United States
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| Posted: Tue Jan 17, 2017 9:49 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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Tore down the 1700 motor to the pistons. Have not split the case. Looks like water damage to pistons and cylinders.
Does not appear to have internal damage as once I was able to pull heads and cylinders motor freed up. Cam and lifters look very good although they will be replaced.
Two questions:
1) From the picture is this a domed high compression piston?
2) Took out oil drain cover and strainer. Seems ok. If it had the type 4 syndrome would you be able to see it without splitting the case?
Thank you in advance |
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JustBuggy
Samba Member
Joined: August 01, 2010
Posts: 849
Location: SF Bay Area, Ca.
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| Posted: Tue Jan 17, 2017 10:00 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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I had the same domed pistons in my 1.7. I wish I would have kept them as the replacement ones I bought are flat top.  |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Tue Jan 17, 2017 11:28 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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Yes, those are the domed high compression pistons. They are 8.2:1 compression stock and will yield 8.5:1 compression just by removing the head gasket and the cylinder base shim. If the ring lands are fine...and they measure good for no collapsed skirts...clean the tops and use them.
They will be either old Mahle or Kolbenschmidt...non better either way. Ray |
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Bermoco
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Joined: September 02, 2014
Posts: 75
Location: United States
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| Posted: Wed Jan 18, 2017 6:31 am Post subject: Re: 914 Motor help... in search of thoughts... |
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| Thank you for your reply. Will measure them. |
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broomhandle
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Joined: August 04, 2009
Posts: 122
Location: Half Moon Bay, Ca
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| Posted: Thu Jan 19, 2017 9:21 am Post subject: Re: 914 Motor help... in search of thoughts... |
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so, back to heads...
If i ran 2.0 crank/cam etc.. and 94mm pistons. the 1.7, 1.8 heads would need to be cut. would this still be around the same displacement as the 2.0 (1971cc)
and as for the bus 2.0 heads. is there nothing to use on them? are they better off just going to somebody with a type IV bus?
looks like 2.0 had 94mm pistons, 1.8's had 93 and 1.7 had 90.
http://www.p914.com/p914_engine.htm |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Thu Jan 19, 2017 10:47 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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| broomhandle wrote: |
so, back to heads...
If i ran 2.0 crank/cam etc.. and 94mm pistons. the 1.7, 1.8 heads would need to be cut. would this still be around the same displacement as the 2.0 (1971cc)
and as for the bus 2.0 heads. is there nothing to use on them? are they better off just going to somebody with a type IV bus?
looks like 2.0 had 94mm pistons, 1.8's had 93 and 1.7 had 90.
http://www.p914.com/p914_engine.htm |
No.....the 1.8s will be close enough with a little unsheouding work to the valves...you should be close enough that a shim adjustment to the cylinder.....which gives a higher or lower deck height.....with get you either spot on or very close in compression ratio.
The 1.8 and 2.0 combustion chamber volumes were very close in size. Fly cutting for the 2.0 will raise the fompression slightly but it will eituer be close enough of you can adjust with base shims. Ahout .040" minimum deck to .045" is ideal. T4y not to have a deck greater than about .050".
The 2.0 bus heads....the problem is that driving them on a bus kills them....cracks, sinking seats...generally issues you do not see with type 4 heads on a 411/412 or 914.
Ray |
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broomhandle
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Joined: August 04, 2009
Posts: 122
Location: Half Moon Bay, Ca
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| Posted: Fri Jan 20, 2017 9:13 am Post subject: Re: 914 Motor help... in search of thoughts... |
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lets say the 1.8 and the 2.0 bus heads were both brand new, what differences are there in performance if they were cut for the 94-96mm pistons.
could the 2.0 bus heads be upgraded with better valves etc to get close to 2.0 914 heads? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Fri Jan 20, 2017 11:25 am Post subject: Re: 914 Motor help... in search of thoughts... |
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| broomhandle wrote: |
lets say the 1.8 and the 2.0 bus heads were both brand new, what differences are there in performance if they were cut for the 94-96mm pistons.
could the 2.0 bus heads be upgraded with better valves etc to get close to 2.0 914 heads? |
If you had "bus 1.8s.....and bus 2.0s.....the difference is very little if you cut the o-ring. 8s to the 2.0 cylinder size. The 1.8 and 2.0 chamber size is within about 1-2cc at most. They both generally run about 52-53cc.
IIRC....they have the same valve size....in fact....also IIRC (im not close to my books)....some of the bus 2.0 may have had SMALLER valves than the 1.8.
The chamber shape is similar enough that the difference is not significant.
The valves on the 2.0 bus and 2.0 914 are the same. IIRC they are both 42 x 36.
The big difference in the 914 2.0 head.....and those with more experience note that it is significant.....is the spark plug angle and slight change in intake port angle of the 914 2.0....very slight difference in chamber shape.....but its valve and port angle.
No....its not simple to transfer the 2.0 914 valve and port angle to the bus 2.0 or 1.8......in fact.....that is what HAM inc does with new 1.8 castings to make exact replica 914 2.0 heads...and that is why they cost so much.
Sure...with welding and CNC machining....you CAN do this with 1.8 and 2.0 bus heads......but you have to know what you are doing, both welding, annealing, machining......and if you are going through that....start with new castings.
Replica 914 2.0 heads on new castings will enable you to take a 914 2.0 engine to better output than stock. At that point for the cost....why would you keep it a 2.0 at all? 2056 or better.
Do not get hung up on 914 2.0 heads. If all you want is stock 914 2.0 performance....you do not need the 914 2.0 heads.
Becaue of better cans, carbs and injection and better tuning and exhaust...you can do STOCK 914 hp and output....with 1.8 and 2.0 bus heads. Ray |
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Bleyseng
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Joined: July 03, 2005
Posts: 4752
Location: Seattle
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| Posted: Sat Jan 21, 2017 8:49 am Post subject: Re: 914 Motor help... in search of thoughts... |
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stock 2.0 bus heads valve sizes are way smaller even smaller than a 1.8 bus head....not a chance they are the same size a 2.0L 914 heads at 42x36.
_________________
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Sat Jan 21, 2017 6:49 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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| Bleyseng wrote: |
| stock 2.0 bus heads valve sizes are way smaller even smaller than a 1.8 bus head....not a chance they are the same size a 2.0L 914 heads at 42x36. |
Thank you.... could not remember if they were larger or not. Either way...going to 42 x 36 on bus 2.0s is not any more or less difficult than doing it to the 1.7s.
Unless they are "new" bus 2.0 heads....they will need new seats and valves anyway. Put in whatever you need. |
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broomhandle
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Joined: August 04, 2009
Posts: 122
Location: Half Moon Bay, Ca
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| Posted: Mon Jan 23, 2017 11:04 am Post subject: Re: 914 Motor help... in search of thoughts... |
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so it sounds like best bet, somebody building a 2.0 without the magical 2.0 914 heads, is to go with 1.8 heads? cut for the larger 2.0/94+mm pistons
and, the 1.8 heads are the exact same on 914 and bus, is this correct? |
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raygreenwood
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Joined: November 24, 2008
Posts: 21520
Location: Oklahoma City
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| Posted: Mon Jan 23, 2017 11:27 am Post subject: Re: 914 Motor help... in search of thoughts... |
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| broomhandle wrote: |
so it sounds like best bet, somebody building a 2.0 without the magical 2.0 914 heads, is to go with 1.8 heads? cut for the larger 2.0/94+mm pistons
and, the 1.8 heads are the exact same on 914 and bus, is this correct? |
Yes......as far as castings go:
1.7L....same casting for 411/412/914 and bus
1.8L....same casting for 412/914 and bus
2.0L.....one casting for bus, different casting for 914.
The 2.0L 914 casting is not to be dismissed as noticeably better in swirl, intake angle and sparkplug angle. I believe IIRC.....that Jake Raby noted that it can make as much as 10% inprovement or slightly more...across the board.
However.....what I have been getting at.....is that if you are looking for and happy with the level of performance of a well tuned stock 2.0 914....and when its well tuned.....its a fun car......then you do not really need the stock 914 2.0 casting.....to get that level of performance.
In factory form.....while the 2.0 914 engine had a good bit better output than the 1.7 or 1.8......there were numerous other issues holding the 2.0 engine back. So while the heads made a difference to get that 110hp with D-jet injection......the exhaust was not deal. Compression was not ideal. Camshaft was not ideal. The plenum inlet angle on the EFI was not ideal. With all or that taken together.....and added to a lot of little items....like ignition was barely adequate, fuel pressure (on all stock D-jet) was not as stable with age as it,should be......and because of all of this in sum total......the injection tuning was not ideal from the factory........a reasonable amount of potential HP and throttle response was left on th3 table.
If the other items are optimized.....you do not really need the 914 specific 2.0 heads to reach 110hp. If you had them....and all of the other tuning....yes it would be a bonus. Ray |
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broomhandle
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Posts: 122
Location: Half Moon Bay, Ca
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| Posted: Mon Jan 23, 2017 12:47 pm Post subject: Re: 914 Motor help... in search of thoughts... |
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Yes, I understand. Its just I basically have 2.0's with no heads...
And I understand, these older cars are what they are. I love them for what they are. but as power goes, a modern VW GTi is just that much quicker than a stock 914. But that is not what its about... I love the sound of the aircooled, the twin carbs...
I sold my 914 with a 1.8 a few years ago, and I just sold my stock-ish 69 bug about 5 months ago and I already miss it....
that is why I just want to get my 914 rolling again, but make it fun to drive with that touch of pep...
im not building a race car, but would like to get as close as I can with what I have and not spend as much as a brand new GTi....
I guess I am thinking go with the 1.8 heads on a 2.0 guts in a block with 2.0 pistons....
does that sound about right?
and would get me to a 1.9.5.. haha
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