need basic head work... Rimco or headflowmasters?

Ghost Rider · Post by **Ghost Rider** » Mon Jun 09, 2003 8:59 am

I have 2 914s now, one with a stock 1.7 engine with dual Weber-IDFs and a 1.8 bus with 1 weber progressive....

the 1.7 has a burnt valve(I think, it runs but has low compression on one side) and the 1.8 doesn't run(don''t know why yet.) if the heads are good on the 1.8 can they be used on the otherwise strong 1.7? or would I be better off just rebuilding the 1.8 and putting the IDFs on the 1.8?

Bleyseng · Post by **Bleyseng** » Mon Jun 09, 2003 10:06 am

The 1.7L has 90.5mm pistons and the 1.8L has 93mm pistons so the cylinder bore in the 1.8L heads is too big.
Just fix the 1.7l if it has the domed pistons as its 82hp. Send the heads for a rebuild to Headflow masters and install 42x36 valves. Makes for a nice motor. The 1.8L is I think 67hp.

Geoff

NextGen · Post by **NextGen** » Mon Jun 09, 2003 11:14 am

Why not use the 1.8 heads and use 2.0 P/C's. I guess you would have to rebuild the heads anyway, but the 2.0 will slip on. On the other hand if you use 1.7 flat top pistons you may have a more powerful 1.7 then the 2.0 if you use concave pistons.
Joe

Griznant · Post by **Griznant** » Mon Jun 09, 2003 11:40 am

NextGen wrote:Why not use the 1.8 heads and use 2.0 P/C's.

Yeah, but your pin height will be screwy because the pistons will be expecting a 71mm stroke/rods and only be bolted to a 66mm. That will significantly effect your deck height. The rod lengths are different, and so is the stroke, and that will play on the pin height.

Maybe my math is off, but I know it won't be a straight bolt on deal.

Later,

G

I

Ghost Rider · Post by **Ghost Rider** » Mon Jun 09, 2003 12:27 pm

the stock 1.7 was 80hp, and the stock 1.8 was 76hp... the difference in hp comes from a lower compression ratio (7.6 vs. 8.5) on the 1.8L the 1.8 heads are definitely better than the 1.7. I guess what I was really asking was which case... is the 1.8 Bus better suited to become a 2056 or 2270 later? is either of them suitable? also, does anyone on here have a 1.8 bus with dual webers in a 914? does it have enough Hp to be drivable... I would imagie it does since my 1.7 wil get a 2nd gear squeak out of tires on take off and it's only running on 3 cylinders at best! I'm trying to avoid sending the heads off until I can find someone I know I can trust... preferably locally in Dallas or Austin... or even Houston!

dstar5000 · Post by **dstar5000** » Mon Jun 09, 2003 12:39 pm

They are BOTH *suitable*.

They both also have a 66mm crank. The larger 2.0L had a 71mm crank.

The cases are the same...

Don

Ghost Rider · Post by **Ghost Rider** » Mon Jun 09, 2003 1:19 pm

ok, I wasn't sure, I've heard how terrible the 96mm pistons were for the 1.7 engine, and I know most of that is due to the heads... which isn't a problem since either way I'll be using the 1.8L heads. but I was afraid more modifications would have to be made to the 1.7 case down the line... will any case modifications be needed to go to 2056 or 2270 for the 1.8? for the 1.7?

raygreenwood · Post by **raygreenwood** » Mon Jun 09, 2003 3:31 pm

The 1.8 heads are not better than the 1.7 heads. They simply have a few more cC's as their only adavantage. They have an inferior quench area design compared to the 1.7. The 1.7'scan easily be ported, still maintain their quench area and the "dimple" that interacts with the dome on the stock pistons, and be almost as large as a 2.0. Since you need to replace theseats on anything you do...simply put larger ones into the 1.7. I run 42x37 in my 1.7. With porting...I have about 55 cc per combustion chamber. With the domed pistons, 8.3:1 compression factory was 8.2...not 8.5...there are no stock 1.8's that will touch it...save for an AN series Euro, carbed 914 1.8....which had 8.6:1 and 85 HP. 3 extra horses is a poor reward for 100 extra cc's, larger valves and .4 compression points. Considering the exhasut port design is identical, the only two things keeping the Euro 1.8 back...was the carbsand the combustion chamber design. The ONLY thing the 1.8's are known to have superior...is a few more cc's and larger valves. Larger valves and new seats are the same price either head, and the shape is better on the 1.7...and you have more metal to start with. Ray

Bleyseng · Post by **Bleyseng** » Mon Jun 09, 2003 3:58 pm

Ghost Rider, he is talking about a 1.8L BUS motor which is 67hp by the Type 4 secrets charts. I know a 914 1.8L is 76hp.
Ray Greenwood makes some very good points about the 1.7L 80hp (I have seen some early books that say 82hp) setup. I have seen lots of 914 1.7L switch to 93mm p&c's and new or rebuilt 1.8heads only to have alot of hp gone! You can tell the difference. Porsche and VW spend alot of time designing that motor and that exact combo works really well. It is even nicer when you install bigger valves as Ray has found out. Dropping the CR down to 7.3to1 with flat top pistons on the EB 1.7, the 1.7 squeeked out 72 hp.
If you use 1.8L bus parts and keep the stock CR the engine is a dog, making 67hp. If you set the CR at 8.5to1 you should be close to 85hp.

You already have a 1.7L so just fix the valves way cheaper.
Geoff

Ghost Rider · Post by **Ghost Rider** » Mon Jun 09, 2003 7:36 pm

thanks for the info... I actually don't know if the 1.8 is a BUS or the 914... the PO *THOUGHT* it was a bus, but only b/c it had a carb....I don't have the car right here(supposed to pick it up soon)I'll definately consider both options....

I understand that if I port the 1.7 it would proably be be better than the stock 1.8... but if I am to go with bigger piston's later... wouldn't it be better to port the 1.8? or is that only true if it's a 914 1.8, not a bus?

I was told the 1.8 heads have bigger ports... is that wrong?

raygreenwood · Post by **raygreenwood** » Mon Jun 09, 2003 8:30 pm

Without porting the 1.7 head is still better than the 1.8 in my opinion. Its has a superior shape. It is not too much smaller. There is really not much that yiou can take out of the 1.7 liter head that will not estroy the built in characteristics that work well with the domed pistons. On the intake valve side, you can unshroud...and slightly undercut the quecnh area by the dimple...but make the transition edges smooth. Yo can take out about twice as much materisal on the spark plug side...and deepen the whole chamber slightly...maybe a milimeter or so...befor the new seats go in. Maybe 10-15cc total. One thing I believe a lot of people are not thinking about...that Bleyseng mentioned, isthat the 1.7 was produced from 68....to what..76-78? They spent a lot of time working on the heads. In some of the very few heads from the early days that I have seen...almost none of which made it to this continent...there were subtle diferences in shape. I have seen at least one head that was Euro carbed for the 411...from 68 that had very much smaller quench area..and noticibly less dimple shape. Many people discount the 1.7...and scoff at the puny domes on the pistons. I can assure you that those little domes ...with the heads...make a huge difference. I have built 1.7's with flat tops...that made te same compression as the injected engine did. They were dogs and the vacume signature made the injection touchy to tune. The dome and head shape ineteraction was optimized about as well as a stock type 4 could be. With considerable tuning on the injection, bigger valves and a good cam...100 hp is not incredibly hard to get on the 1.7. The 1.8's were more of an afterthought. They were an emissions response. Larger CC's in the 1.8 to keep the torque up...while reducing compression and changing the combustion characteristics to allow lower nox emissions. Most people who are building larger engines prefer to start with the 1.8 simply because there is less cutting and serious work to go larger on But bear in mind, to correctly reseat valves, metal must be removed to go slightly oversized on the seats. You can run out of room faster on the 1.8. Just some thoughts.. They are bothy adequate. Ray

Ghost Rider · Post by **Ghost Rider** » Tue Jun 10, 2003 7:03 am

thank Ray, you've been a great help! I have a lot of ideas to kick around now... do you think putting the 93mm pistons on the 1.7 rods/Shortblock with the 1.7 heads is the way to go for now? or just leave the 1.7 completely stock? are the 1.8 rods shorter?
if I will gain nothing by using 1.8 parts... I will leave both engines stock and get the heads fixed on the 1.7 for now... and then slowly build up the parts to convert the 1.8 into a 2056 or 2270... but I may still use the 1.7 heads... I was always under the impression that the 1.8 heads were more like the 2.0 heads and thus wouldn't need work to attach a 96mm... who knows what I'll really end up with at this point... I will deal with a stock engine for now anyway.

Bleyseng · Post by **Bleyseng** » Tue Jun 10, 2003 10:37 am

The only thing the 1.8L heads are like the 2.0L (914) is the register of opening for the cylinder. The 1.8L will take a 94mm or 96mm cylinder.
Yes, the valves are alittle bigger but are not like the 2.0l.
If you are using the 1.7L use the complete combo! I would install bigger valves (42x36) and port the heads some, both intake and exhaust. This is a good combo from what I have seen. There is one guy who runs a hot 1.7L 914 that does really well with it. As Ray has said you can get 100hp with this combo.
The dome piston and the small chamber are like the supersquish pistons vs the standard flat tops.
If you want higher revs the valve springs are what kill these motors at about 5000 rpms not the Djet. The Djet is good to 6000rpms.
Geoff

Ghost Rider · Post by **Ghost Rider** » Tue Jun 10, 2003 2:22 pm

I do not have the D-Jet unfortunately... I have dual webers though... which is actually ok by me... later I suppose I will have the 1.7 heads ported and the register opened to accept 96mm pistons... and the 1.8 bus will go with who ever buys the leftover parts car... since it seems that the consensus of the forum is the 1.8 kinda blows compared to the 1.7... thanks again for everyone's input, this has been extremely informative... I'm still a babe in the woods on these bad boys!

raygreenwood · Post by **raygreenwood** » Tue Jun 10, 2003 2:44 pm

There is something you can try. What do you really want to spend on pistons? Good 1.7's with domes are getting hard to find...good quality ones that is. If you can stand the cost of them...having your pistons made by Kieth black or...Dang...who is that other one...anyway...its about $390 for all four pistons. But they will be to your specs. Make then 93mm (1.8l size) with .020 factory oversize.....but with 1.7 domes on them. Simply send them a 1.7 piston to duplicate, but give them the outer diameter plus factory oversize of the 1.8. Use the cylinders from the 1.8...have them honed .020 over for the new pistons. Have the 1.7 heads opened up for 93mm...but be very careful to leave the deck alone. The compression generating capability becasue of the added quench area of going to 93mm...and the domes..will let you achieve almost 9:1 compression...which can be adjusted down with shims under the cylindres. If thissounds expensive...bear this in mind. Getting a known good quality set of piston cylinders and rings...with domes...1.7l...is running about $385 a set. About $289 for flat tops...which are almost as hard to find...and not any better than dished pistons. So that compares to $400 for custom+ $80 for honing+ about $25 for rings. ..about $500. Thats $100+ more...yes...but very nice. Ray