94mm Pistons and Cylinders on a daily driver Friday, 21-Apr-2000 01:27:38 writes: Has anyone here ever used 94mm (a or b) pistons and cylinders in a daily driver engine? I was curious as to what kind of mileage you got out of your set, and what problems if any were experienced. I have heard that they are bad and don't give the service or longevity of 90.5's. And I have also heard that 94's are just fine and give plenty of performance and longevity. I know that "daily driver" has multiple interpretations, but when I say daily driver, I'm talking driven anywhere, any time. I'm interested to hear from everyone. Happy hot rodding! Matt Harris

Message thread:

94mm Pistons and Cylinders on a daily driver (Matt Harris) (21-Apr-2000 01:27:38)

Re: I have had no problems with 94's. I had a 1776 125 cam welded heads and put 94's on it I noticed no difference between the too. (n/t) (DLH) (21-Apr-2000 01:45:27)

Matt, Ive run 94's for the last 10 years when I.... (Greg Ward) (21-Apr-2000 02:44:43)

Excellent, Greg. Just the info I was looking for. Thanks a bunch..... (Matt Harris) (21-Apr-2000 02:49:25)

Ok Matt, heres some more info.... (Greg Ward) (21-Apr-2000 03:32:32)

Yes Greg, my C/R is 6.7:1 and my 2007cc still overheats, but that's another story..... (Matt Harris) (21-Apr-2000 04:40:37)

Matt ,you want some more real world experience about temps??!!! (Greg Ward) (21-Apr-2000 04:58:58)

Oh, and I forgot, I replied to an old post of yours and I said +3pts on C/R would wake it up, I don't know what you think but in light of my temps how could that hurt??????? (n/t) (Greg Ward) (21-Apr-2000 05:12:28)

Very true. (n/t) (Matt Harris) (21-Apr-2000 06:46:51)

Holy crap Greg, that blows me away!!!! (Matt Harris) (21-Apr-2000 06:45:51)

I ran some unleaded race gas thru my street car last summer. Real HOT day couldn't hardly get the stupid thing to heat up to operating tems. Fouled the O2 sensor. Ran 80 mph all the way home. 2 hours. (beetlejuice) (21-Apr-2000 09:57:03)

How many miles are on your 94's DLH? Any problems? What's your compression ratio? (n/t) (Matt Harris) (21-Apr-2000 02:45:45)

Everybody has different views on what's ok! (Clyde Berg) (21-Apr-2000 18:37:08)

sweet clyde, i here ya. i wish we had more hard numbers on these various parts. (n/t) (bergboy) (21-Apr-2000 18:58:06)

Thank you Clyde for sharing your info with us. Every engine I have worked on with 92 or 94 has had ring problems so I too do not recomend them (n/t) (Steve Hollingsworth) (21-Apr-2000 21:42:07)

Re: Mine have around 70,000 miles on them and they look brand spanking new. They're round, straight and beautiful. (n/t) (John Rayburn DKP3) (21-Apr-2000 22:23:48)

Hey Clyde, will GBE be selling this bentley book your speaking of? I need a copy of this as soon as it hits the presses....sounds like some good info. (n/t) (John Pagnanelli) (22-Apr-2000 01:33:37)

Matt, Ive run 94's for the last 10 years when I....

Friday, 21-Apr-2000 02:44:43 writes:

ran the car on the street to work everyday and everywhere I went (it was my only car) I did 90,000kms in 3 1/2years. No problems,but I always serviced it very regularly, changed the oil,timing, and a head torque each time, just the bottom row of studs cause that's all you can get at in the car.

The engine was a 1915 with kadrons.

The next set lasted another 3years even though I only drove it to the races(some were actually 1500kms away) raced and drove home.

1915 44IDF's Street elims

But I attribute this to the fact that I was constantly running through dirt return roads back to the pits all the time and sometimes even to get into the track.

I am now on my 3rd set and they have done about 10,000kms since new, when the engine was pulled down for the start of this year they went straight back in with a hone and new rings.

3 sets in 10years $1000 bucks!!

I'm pretty happy with that.



When I was driving it only to the races and racing and driving home


Do you know by chance what 1 km is equal to in miles. I'm in So. Cal. and we are pretty behind when it comes to the metric system in distance. I am a scientist by trade, but do not really want to look up in my books to see the conversion. Thanks again Greg, excellent post. Is 3 years considered good for 94's though. Over here, 3 years would be about 36,000 to 45,000 miles, and that doesn't seem to good. Is it?

Matt Harris


Ok Matt, heres some more info.... Friday, 21-Apr-2000 03:32:32 writes: Firstly :- here's the coolest converter I've found and I just found it then.It has the three main conversions I am always looking for when talking about Vw's. Miles/Kms, Pounds/Kg & Fahrenheit/Celsius. http://home.earthlink.net/~jimblish/convert.html Now, 90,000kms actually equals 56,250 miles, which I don't think is too bad, but what I didn't say was the only reason I changed them at all was I was starting to get really serious about racing. One of the old sets of Barrels and pistons are still on my spare engine!! They have had new rings and a hone again but I couldn't even think of how many miles they have done all up now. One thing that will happen, and I suppose it will happen to any barrel and piston, but if the engine is severely overheated or seized then they could cop a hiding and be stuffed (that being the technical term for what happens!!) But I will say again, many people have opinions on this longetivity and I think it is all about how you treat the engine. I have had friends who would sit on 110Mph on the freeway and floor it up hills, never tune it, throw it sideways at every opportunity and do donuts in the carpark until they can't see where they're going. Needless to say their engine didn't last long. My engine builder has built around 1500 1915's in the last 15 years and they all use 94's, some of the kadron ones are still going after 9 years driven everyday. The philosophy is, tune it ,look after it, don't be silly (I.e floor it up a 1000ft hill with no oil cap)and it will last a long, long time. FYI, we must have better fuel over here but The C/R of the 1st 1915 with kadrons was 9.0 The C/R of the 2nd 1915 with webers was 10.5 The C/R of the 1915 for the last 5yrs is 11.5-12 I think you said in 1 post your C/R was 6.7? Is that right? Hope some of this helps Matt, if you want anything else send me a mail. Greg..... Greg Ward

Matt ,you want some more real world experience about temps??!!! Friday, 21-Apr-2000 04:58:58 writes: I personally think your engine is running sooooooo cool you wouldn't believe. I mean what is "overheating" or "running hot" anyway. I read that other post and you said 225 at 75Mph on the freeway. Ok that equates to 107.2 deg Celsius at 120 Kph. That is unreal!!!!!!! Shall I scare you with my figures???? Bear in mind that these ARE real, I do it every time I drive it. My oil temp around town with the bootlid open at the top is 100-105 degrees Celsius. or 212-221F Lovely, right in the green on the guage, and more importantly, in the specs of the engine builder. On the freeway with my 1.21 4th gear I would normally sit at 56Mph (90kph) on a freeway that is 110kph, and the oil temp is 125C constantly for 500km till my destination. Or 257F for 312 Miles. That is at the limit of the green on the gauge and still more importantly ok with my engine builder. The oil that I use is rated to 160C or 320F so I am always ok, but obviously I usually change it after every meeting. I have run the engine at 8000rpm around a circuit, (I was in the middle of a race and the car was double entered so no time to cool down) at 150C or 302F for 3 1km laps and I hurt it. Just started to nip a main. Never seized still drove it home, but it had to be torn down. There ya go So your 225F is sooo cool to me.. Greg Greg Ward


Holy crap Greg, that blows me away!!!!

Friday, 21-Apr-2000 06:45:51 writes:


Oh my gosh!!! Your oil temp was at 300+ and you didn't pull a head stud or seize it!!! And 257 for a 100 miles??? Oh my gosh, maybe I am running super cool. But I have always thought that 190 is normal and cool. 225 is too hot, and 250 head studs start pulling. Maybe I am just anal about my oil temp or something. There is also another simple way to check the oil temp too. If the dip stick burns you then the oil is too hot, and needless to say the oil temp burned me. Stay cool, dude. See ya.

Matt Harris


I ran some unleaded race gas thru my street car last summer. Real HOT day couldn't hardly get the stupid thing to heat up to operating tems. Fouled the O2 sensor. Ran 80 mph all the way home. 2 hours.

Friday, 21-Apr-2000 09:57:03 writes:

Maybe some unleaded will help. I had to keep my old low compression 2110 at about 60 MPH or 100Km or else overheating in 20 minutes. I even got a new AS21 block, still hot.

I'm sure a RAMVAite will hop in about his T4 motor running cool, and it probably does...

Does the auxilliary cooler really work? Anyone?



Everybody has different views on what's ok!

Friday, 21-Apr-2000 18:37:08 writes:

Most VDO gauges are inaccurrate compared to real numbers. If anyone thinks that an acceptable oil tempurature for a motor is 300 degrees then they are sadly mistaken. That temp. will fry a motor. I know I've done it. Normal oil temp for a daul port vw aircooled is 210 degrees, and a single port is 220 degrees. If you check with oil manufactures they will tell you that most petroleum base oil will start to break down at 250 degrees, and I'm sure some of you are thinking what about synthetic oils? All of our testing that we have done shows that oil temp goes down but head temps increased considerably, remember that an aircooled vw motor uses the oil to draw the heat out of the heads. Synthetic oils are designed to repel heat. I have personally tested a number of different motor combination in the last year, testing different tempuratures vs hp readings. I found that at normal operating temp. produced higher hp readings and when we raised the temp up only 10 degrees the motor lost around 7-8 % of the hp. and they higher we went up the greater the loss. Most people could not tell the differance by driving the car if it did loose 7%. I have personally tried running a street car with 92's and 94's "cuz'every body was running them and they all told me about all the milage they had on thiers and it was still trouble free" So I decided to go against all of Gene's recomendations and try it. After only 8000 miles I could feel the differance in hp from cold to hot. The 92's were obliviously worse than the 94's and both of the motors were still running and would have gone more miles when I took them apart but why leave them together they were 20% down on power when hot. When I put the next motor together I used 90.5 p/c and after 50,000 miles it had the same power hot as it did cold. This motor that I am speking of now resides in my Race Car, it has been in there for 14 years and it still has the same p/c set that it did when it was built origially. With the exception of one cylinder that cracked from a major lean condition, and one piston was replaced from a broken valve. I do strongly agree with Greg that the life of a motor depends on how hard you want to abuse the thing. Alot of this info on tempuratures vs hp will be available from Bentley Publishing in the next year or so. The book will also delve into different combos and there effect on temp.(ie:adding Daul carbs, bigger p/c, ratio rockers, different compression ratios, etc.)The book will not be written by GBE, we just did alot of the testing to get the numbers.

Clyde Berg

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