.90 ops

[hugh hargett]

Saw someone trying to give a working one away. I told them they were crazy. Are they or am I? Ops .90's were once considered the goodies . Im havent looked at nitros in along time. Wats the scoop on the old .90 ops's are they still a viable option for a 100 mph boat?

Hugh

 

[ALLAN YUEN]

Saw someone trying to give a working one away. I told them they were crazy. Are they or am I? Ops .90's were once considered the goodies . Im havent looked at nitros in along time. Wats the scoop on the old .90 ops's are they still a viable option for a 100 mph boat?

Hugh

No OPS only stock speed about 60 to 80mph If you want modded piston/sleeve , carb, and crankcase so can run increase 15% to 20% rpm will run +90 mph contact Steve Wood , Andy Brown or Frank Orlic work modded good job well and extra more pay about 100.00 to 250.00 Good Luck!

 

[hugh hargett]

Not stock allen but you said GOOD LUCK! does that mean its a waste of time compared to the newer cmb's?

 

[David Bryant]

OPS engines are generally good, and provide decent performance. However they are a little behind in design compared to the current CMB models. Much of the current OPS line is still much the same product as was manufactured 20 years back.

The .45 model, for example, is essentially same design from 1980's/1990's, only now has incorporated a drum valve induction rear plate assembly (which is great). However the carb mounting bore uses same I.D. as original design, consequently allows for no increase in intake bore which would help increase power.

Although I have run OPS .45 engines for a number of years and have been thoroughly happy with the quality and performance. I use RPM rods. Skirt the piston on the rear side. Use a stock OPS .45 speed venturi combined with a very good Carl Brey exhaust throttle (you can even use an OS Max 4E carburetor). They really fly using 50% nitro. Have never had one break apart on me either. I have two .45's that I'm still considering running, most likely in mono class exclusively.

I'm not sure how your older .90 marine compare to the current OPS .90 "Bi-Metal" Marine model. The new .90 incorporates a drum valve and other details, looks cool, not sure how performance compares to current CMB models.

I use current Picco and CMB engines as well.

 

[hugh hargett]

yes i jsut sold a nice picco 67 a few months back. It was brought as a gift for alan hobbs.

 

[Andy Brown]

Big Block OPS 90 = Good. With the right mods it make as much power as any other 90. Biggest disadvantage is the physical size and weight.

 

[hugh hargett]

OH OKAY! I understand now. Does this bi metal model have to do with weight savings or strength?

 

[David Bryant]

OH OKAY! I understand now. Does this bi metal model have to do with weight savings or strength?

I believe this upgraded metallurgy provides different expansion properties (than traditional "ABC"- Aluminum/Brass/Chrome configuration), supposedly yielding higher performance. OPS site claims (quote): "a unique liner made from aluminium then a small coating of brass and then chromed, the engine has greater rpm and starting due to the good expansion and contraction of the new liner."https://www.mantuamo...arine_1276.html

The .90 Marine "Bi-Metal", as the description notes, is a .90 displacement engine but incorporates the (older) .80 crankcase cyl/head configuration to save weight (886 grams).

The OPS .90 Marine "Big Block" engine (Andy is referring to) is a different model, it has slightly larger crankcase area and cyl/head configuration, consequently greater weight (1250 grams). Not sure how the "Big Block" differs from the "Bi-Metal" internally?

https://www.mantuamo...ne__90_527.html

 

[Tim_Duggan]

Someone "in the know" told me that the OPS80 to 90 modifcation had been tried previously in a Ducted Fan Aircraft configuration and it was less than ideal. I'm not a fan of 3 piece crankcases either.

I started racing in '93 and OPS were very, very popular back then. Sadly, the crankcases haven't changed since then! They seem to have gotten VERY good value from their crankcase moulds!

 

[David Bryant]

Someone "in the know" told me that the OPS80 to 90 modifcation had been tried previously in a Ducted Fan Aircraft configuration and it was less than ideal. They seem to have gotten VERY good value from their crankcase moulds!

you're exactly right, OPS has saved a lot (financially) by using the same moulds for years now. I remember the ducted fan model, that's exactly what the Bi-Metal .90 looks like (only marine)

 

[charles siler]

Here are a few upgrades for the older black head modles that have mods from the factory . pistons with extra boost ports knife edged rod and sleave mods . The pics show old and the new parts

 

[charles siler]

Yes on request talk to Dave At Got nitro .com

 

[David Bryant]

Here are a few upgrades for the older black head modles that have mods from the factory . pistons with extra boost ports knife edged rod and sleave mods . The pics show old and the new parts

wow, that's very cool. From the factory?

 

[Scott Miller]

Here are a few upgrades for the older black head modles that have mods from the factory . pistons with extra boost ports knife edged rod and sleave mods . The pics show old and the new parts

wow, that's very cool. From the factory?

Yes from OPS.