IMSA merkur.......

[anglin]

What's sorta interesting to me is that none of the "vintage photos" I've seen of the cars in Mac Tools trim sport the number 11 of the car currently in the museum. It's really an academic point, as the bodies were interchangable - just one of those little details that I've noticed.

I can fix the "I've never seen," Brad. Here you go!

[DPDISXR4Ti]

Damn you Brad! Ya beat me by a second.
As for the use of a cast iron block, probably due to Homoligation rules.

I'd suggest "Brillant minds think alike", but then, what would my excuse be?

As for the block, I suspect it was more a case of an AL block simply did not exist! Whipping a custom race block together is no small order. The tall deck block was never used in any production vehicle, so I don't think homologation rules really applied there. I wonder if they applied at all in this series?

[DPDISXR4Ti]

What's sorta interesting to me is that none of the "vintage photos" I've seen of the cars in Mac Tools trim sport the number 11 of the car currently in the museum. It's really an academic point, as the bodies were interchangable - just one of those little details that I've noticed.

I can fix the "I've never seen," Brad. Here you go!

Way cool! Where'd you get this one Chris?

If the file name is a correct indication, this pic is from Columbus Oct '88. That would make sense, as it was likely one of the very last races for the Roush Merkur, and so that's the car that was put away when the season was done and now rests in the museum.

[xr4racing]

Looks like I started something.

I see you guys found the photo archives at http://www.racingsportscars.com. I thought it was Brad that turned me onto it a while back. Great site.

Ah ha.. 1988 Daytona 24hr race lists both the 4cyl and V8 XR4Ti's as I'd mentioned earlier. Sure enough it looks like it was the V8 XR4Ti that was 1st in GTO with Scott Pruett, Pete Halsmer, Paul Miller, and Bobby Akin driving. Apparently the 4 cyl car didn't finish.

The Roush cast iron block(s) in Detroit did not look like a stock 2.3 block to me. It indeed has an alu. head as you can see in the photos I took. Probably 2 valve as I've heard the 4 valve head was never developed enough to run it.

The 'official' published data was 2.5 liter, 490hp, 8k rpm, 2,350lbs. Could be they were sandbagging judging by how they pounded the competition.

The second car I said I am aware of is reported to be 'that' Daytona V8 car by a very reliable source. Some chance of an appearance at Carlisle.

Stay tuned!

Brad, it looks like Pruetts car was #11 the entire '88 IMSA season. Del Mar, CA was the last race. I was there!

Peter

[MerkXRTurbo]

2.5 lt Cast iron block but I think it was the taller motorsport block, aluminum ARCA type head with 5 cam towers with removable caps.
As for the videos, I've been looking for years with no luck yet.

That's right, 5 cam towers. I was reading that recently, but forgot. It was actually saying that ours flex in the middle... that is, however, at revolution speeds that none of us would ever even consider running.

[John Brennan]

Del Mar, CA was the last race. I was there!
Peter

So was I! That's where we won our first Merkur-- remember the prize give-away?

[DPDISXR4Ti]

Del Mar, CA was the last race. I was there!
Peter

So was I! That's where we won our first Merkur-- remember the prize give-away?

That was rather rude of you not to say hello to Peter while you were both there, don't you think John???

[John Brennan]

Yes, of course-- callow youth, and all that-- Tut, tut! I guess he should have waved; then I might have seen him!

One of the most memorable things about the Del Mar IMSA race happened the previous year. Al Holbert had just been killed before the race (plane crash), and there was his 962, sitting there driverless amidst the forlorn crew... I later saw that car at the Barrett-Jackson auction, and needless to say, spent many long moments looking at it again...

[got_xr?]

Looks like I started something.



The 'official' published data was 2.5 liter, 490hp, 8k rpm, 2,350lbs. Could be they were sandbagging judging by how they pounded the competition.



Peter

everything i've read on turboford as hinted roush was at 1000hp then detuned to 750 for competetion... has anyone else heard this?

[xr4racing]

Hello John (and all),

Well I didn't win any car! I lived in LA between 1978 - 91. I used to go to the Long Beach Grand Prix, the Monterey Historics, and Del Mar. I remember getting right up to the fence at Del Mar, right at the concrete barriers lining both sides of the track, and watching the cars roar by.

I started my track hobby in about '82 out there. Been on Riverside, Willow Springs, Laguna Seca, and Sears Point many times.

Back to the horsepower specs..

Ok, likely racers never really tell what they've got. By 'official' numbers I mean what Roush was likely telling the press. I got those specs from an article, specifically on the Roush XR4Ti's, in the '86 Trans-Am at Road America event program. Maybe they're wrong.

The '87 Mac Tools XR4Ti press kit I have (which is FABULOUS) says 150 cu. in., 4-cyl, turbocharged and intercooled, 500 hp, 8000 rpm. This is a Mac Tools corporate press kit. I doubt if they just made up some numbers. They likely got them from Roush.

As a side note the Trans-Am requirements for the XR4Ti state: 2500cc two valve.. 2350 lbs, 2500cc four valve.. 2550 lbs.

There's also a spec sheet on one of the Trans-Am Camaros. 310 cu. in., 585 hp, 2600 lbs, etc...

XR4Ti... ~4.8 lbs/hp
Camaro... ~4.5 lbs/hp

I assume they reference flywheel hp (typically). Either of those power to weight ratios would be hugely fast... as they were.

Stock XR4 ~16.7 lbs/hp

Peter

[RyanH]

Fabulous photos and trips down memory lane! My father and I were at all the Trans-Am and IMSA races that took place at Mosport over the years, and we still have that exact program that's pictured in the first post. I think we also have a picture of one of the MAC cars cresting the infamous Turn 2 backwards...