Thanks for all the info on the ZR1 posts. I have found a few Z's that I am debating on. One is a 92 that has had a tone of stuff replaced with around 55k on it. It has had clutch, ujoints, injectors, starter, fuel pump and a few other things. I am wondering if the drive train replaements were because of abuse.
The other is a 94 that has had mostly routine maintenence with 60K on it. Does the 94 use r-12 or r-34? Can I assume that the 94 will need similar maintenence? I am attrracted to the 94 because of the extra hp. Is it worth it?
If were talking horse power then go with the 94 when comparing to a 92. The
92 car is the heavier of all the ZR-1's made with the lowest hp. Your noise deadners and ASR made the car alittle heavy.
1993 was the last year they came with R-12. Everything from 1994 on up is R-134. 93-95 are the more sought after ZR-1's, but get what you can afford. The 93-95 ZR-1's also have the 4-bolt mains while the earlier models have the 2-bolt main. I hope this helps on deciding what you're after.
If you can afford it,I would go with the 94 because of its lower production numbers,more comfortable interior,slightly better build quality,a little more power,etc. Unless you plan to build a 415",the 2bolt vs 4bolt difference is pretty much irrelevant since the strength difference on a LT5 is very minimal.
Definatly go with the car that is in the best shape and in the most original condition. 94-95 cars are definatly lower production cars and already have the more desirable 5 spoke wheels most change to, including me. The actual HP the car produces is kind of the luck of the draw... some 90s, 91s, 92s have more than some 95's and vise-versa eve n though the 93-95s are rated higher. If the 94 is in as good of shape as the 92 at the same value, go with it because of the lower production, but if the 92 is a better car in price and condition, I would say that is the car to get then. Just by the most original unmodified car you can get.. unless you are building a race car, I cannot stress this enough after owning many ZR1s in all forms.. Get one that was just driven, not raced.
I went out on a limb and purchased a "tuner" vette. I bought a DRM 450 for 23,900 from Buds. the car wasn't as immaculate as some others (worn bolster, a few paint flaws) but overall it was very nice and runs well. it already had a roll bar (cop trap, can't put the top in the factory holders), the nice chrome 5 stars (I would go polished if I did this again), and the following DRM mods:
63 mm TB (probably doesn't help, but doesn't hurt either)
ported intake, inj housing
poly bushings
lowered
braided lines
DRM charged 10k for this work, and the car had 64K miles. the only problem I had were the 3.73 gears which had the small pinion shaft witha a "sleeve" which failed (very common) so I went with 4.10 super dana gears which make 6th gear more useable and give the car a nice bottom end off the line start. (but probably slow it down due to traction problems).
right now is a GREAT time to buy ZR1s people are dumping them to buy the 2002 Z06s which is fine. that 94 car just sold for under 30K which is pretty cheap for that year. shop around, and you will find a great deal!!! :D
Location: Santa Cruz, CA Norcal Vettes Corvette Cowboy
Re: Is the 20 HP Worth it? 94 or 92? (wm_sorg)
I may be wrong but I belive that I have always heard that the 90,s were the fastest as a general rule. The other years got heavier and that took away any advantage the 20 hp gave them.
Jeffy'
Now, I’m not so sure of that the 90's was the strongest, I would like to really see what it could do against a 95 with the Dunn heads. I understand the cars with the Dunn heads were the most desirable and the stronger ones out of all the ZR-1’s, now I’m talking about totally factory stock
They are also the most fun stock. Get the '90 and let Aaron or Brian (or Jeal/LPE/Rippie...etc) do some magic on it. It probably has been abused a little, but that would just make it fun. No need to baby the car :)
Now, I’m not so sure of that the 90's was the strongest, I would like to really see what it could do against a 95 with the Dunn heads. I understand the cars with the Dunn heads were the most desirable and the stronger ones out of all the ZR-1’s, now I’m talking about totally factory stock
Even if you have Dunn Heads that doesn't mean anything if the cams aren't degreed right. I have been in cars with Dunn Heads and they were DOGS, and driven some 90/91/93/94/95 with Brimal Heads that ran like a raped dates. You need the ultimate combo in 95 with Dunn Heads, cams degreed perfect and the rest of the car to be built on Wed. :D to have something worth talking about.
However on the average your 90 ZR-1 due to its weight advantage is usually the quickest of all the years. Those darn Good Year Gatorbacks seen to allow just enough wheel spin to put the car in the power band. :)
I am personally biased. I have a 95 red/black with Dunn heads & stock exhaust (K&N filter) that dyno'd at 361 rwhp and 356 rwtq at SGC. I would say that the cams are degree'd correctly and it runs VERY well. I use it as a daily driver. I just went to the Daytona 500 and got 25 mpg at 77 mph there and back. It has 53,000 miles and is a different car than I have driven anywhere else--for stock. I am going to give one last serious chance at selling it before I deploy. $34,900.
Guys, I’m not here to put up any flame or debate! Like I said in my earlier post, seems to me that cars with Dunn heads have to produce a pretty stronger numbers. With a 361 rwhp, doesn’t the equal out to 435 horsepower considering there’s a 17% drive train loss?
very stout indeed!!! didn't the dunns heads feature a "pocket port" shape that flowed a bit more?? could some more enlightened folks post how many cars had these heads and approx flow advantage. I seem to remember about 5% better intake flow. the 93-95 cars have an edge in top end IMHO while the 90s get with the program a bit quicker and feature a stronger ZF 6 spd. the 90's are at "give away" prices for a legit supercar. AND I just missed a 94 for under 30K, the ZR1s are becomming a great "bang for the buck" car which is ironic considering the nosebleed prices back in the early 90s. TIA for any details concerning the DUNNS heads.
What I read in the past, there were 130 cars in 1995 built with Dunn heads.
Here is a copy of the post I kept for reference:
Birmal Foundry made the heads for LT-5’s except for the last 130 engines. The Birmal Foundry announced they were going out of business in 1992. Mercury Marine immediately placed an order for a year’s supply of the heads and then GM contracted A.L. Dunn to make the heads for the remaining engines. Lotus modified the tooling and turned it over to A.L. Dunn which is another British Foundry to finish off the production of LT-5 Heads. A.L Dunn took Birmal’s tooling and made changes to resolve quality problems, and began making cylinder heads for MerCruiser. The remaining cast heads have more material (if porting is desired) and better flow than the Birmal heads. Also, on the Dunn heads they fixed the cam chain tensioner rattle problem by including the fix as a part of the new heads. The Dunn heads were just a more refined head and only found on the 95's, mostly the last 100 cars. Birmal made all the rest. If you owned one of the last 100 cars made in 95 then your chances are real good that you have the A.L. DUNN heads. I understand the earliest VIN # for a 1995 that I know of with A. L. Dunn heads is #161. They were not consistently installed, so some later VIN's in 1995 had Birmal heads installed. As far as I understand it there were no Dunn heads in the 94 cars. Graham Behan (Lotus engineer now working for LPE) and he said the Dunn head cars are very strong (stock) and will match, if not better the performance of the 90’s ZR-1 even as the 95 cars got a little more luxurious and heavier. Also there has been some talk about the A.L. heads flow anywhere from 5 to 8 horsepower or even more over the Birmal heads. Having a car with A.L. Dunn heads were unimportant to most people, but this is another item that separates them as far as the difference between some of the 95’s and earlier cars.
I am not the expert on this but I have done a lot of research. Short recap--Birmal went out of business and there was a need for a new head supplier. As you know, Birmal heads required machining prior to final assembly on the engine. This lead to variances. As GM had to change suppliers they decided to make some updates to the heads. One was to make the "machining" changes cast into the design (i.e. direct bolt on as they were flow matched to the other in/out parts). Another was to update the cam chain tensioner with a reservior to retain oil for "dry" starts and eliminate cam chain rattle at start up. Both heads were replaced with Dunn's eventually. The left head was phased in first then the right--it was possible to get one of each (Birmal left/Dunn right).
Now for the real skinny--two cars identically configured (cam timing...etc) with and without Dunn heads should give the Dunn heads a 5-8 hp advantage. In real life does this matter--probably not. There were approximately 130 MOTORs configured with Dunn heads (As of yet don't know if this is left and right or left or right). There is no sequence number of VINs with Dunn heads. They were built and put on racks of 3. As they were loaded at the plant and unloaded to the factory they became interdispersed in the production order. There is a good chance a crate motor has them. This is the only known difference, from the factory, in a 4-bolt motor that I know of. One day I speculate this will make a difference in the collectability of the cars since it is the only difference, and if you wanted to modify the engine it gives you more material to port.
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Is the 20 HP Worth it? 94 or 92?
