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crashbash
david bash
st. charles
(215 posts)

Registered:
01/28/2008 10:53AM

Main British Car:
1979 MGB Rdst V8 project, 1968 MGC GT, 1969 MGB Rd olds 215

engine build?
Posted by: crashbash
Date: July 03, 2008 03:55PM

Have been following along forever A question about engine build. I have 2complete olds 215s, heads and crank from 300 buick, 215 buick heads. Would like to build 5liter but cash is the problem. Thought of stock olds engine with a little more cam, head work, blue printing, balance. Should be good for 200hp do you think? Would like to save 300 stuff for later 5L engine build. So then I'm thinking 100 hp nitrous for occasional insanity needs. Hmm aluminum flywheel would be nice too. Problem is it seems I would need forged pistons for nitrous? So how would any of you approch this engine build? Money is a problem or this would already be decided. Have narrowed pontiac limited slip with discs,GM WC T5, tweeked stock front end powder coated alum. Got to make some decisions, spend some cash and get on with it.


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: engine build?
Posted by: NixVegaGT
Date: July 06, 2008 08:24PM

I think if I was going to go with Nitrous I'd consider leaving the compression the way it is. I'm not an expert on Nitrous but I think it's better to have lower compression. Hopefully someone will chime in.

One option is to give the 215 a rebuild. The stock 215 puts the pistons about .040 below the deck. I've been considering building a 215 with the crank offset ground 0.020 under and add 0.040 on the stroke. Cool! Then with a 0.040 overbore you end up with something like 225 ci. and way better compression. Just something to consider.

The Olds heads flow a little better than the Buick 215 heads. You could use the 300 heads. I don't like the overlap of the combustion chambers on the stock 3.5" bore. That's just me. It's got to be a problem but a lot of guys have used them on the stock setup with good results. It could be the increase in flow makes up the difference..


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5833 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: engine build?
Posted by: BlownMGB-V8
Date: July 07, 2008 11:36AM

Nick, I think you meant the Buick head flows better than the Olds. Worth noting is that CC now makes a "Beehive" spring and it can probably be fit to the Olds head, meaning we now have good springs for that head which will be a tremendous help. Also by overlap are you referring to the squish area? Buick intentionally designed their combustion chambers to use this effect, which is also why they used dished pistons. The figure often used for the squish area is .040" so with a .010" (stock) metal shim head gasket that's just about right, allowing for subsequent head and deck re-surfacing.

Jim


crashbash
david bash
st. charles
(215 posts)

Registered:
01/28/2008 10:53AM

Main British Car:
1979 MGB Rdst V8 project, 1968 MGC GT, 1969 MGB Rd olds 215

Re: engine build?
Posted by: crashbash
Date: July 07, 2008 04:40PM

O guru Jim B I am indeed honored.........you other guys too. I guess my question is really to open a can of worms among everyone with soo many ideas.

Can I build an olds 215 to 200hp tweeking stock components? Can I add 100hp nitrous shot to that and survive? I was told I need forged pistons to put the juice to it. Forged pistons $1k+..from one of our beloved sources --WOW-- 10 to 1 compression I figure with this bore/stroke rod/stroke ratios.... You'd think this could be 10k rpm engine. Is it to my benefit to use a chevy sb rods with stock stroke for strenth?, then I will need some custom forged piston I guess. Roller cam availible? for better cam profile. etc. Seems I remember bits and pieces of later buicks cross over to these engines. Anyone have the entire list?

Don't think it's good idea to put 300 heads on 215. The valve overhang the stock bore don't they? Want to build 5L out of 4bolt main Rover engine some day. Is the 3.9L a 4bolt or do I need to go to the 4.2L. Have 92 range rover county 3.9L I paid $1500 for 50k miles ago, may just pull that engine and sell off the body/ supension parts.


MGBV8
Carl Floyd
Kingsport, TN
(3789 posts)

Registered:
10/23/2007 11:32PM

Main British Car:
1979 MGB, Buick 215

authors avatar
Re: engine build?
Posted by: MGBV8
Date: July 07, 2008 11:01PM

Not sure I'd trust the bottom end with nitrous.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5833 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: engine build?
Posted by: BlownMGB-V8
Date: July 08, 2008 12:47AM

Mike Domanowski is the man to talk to about nitrous. A few years back he swapped his Olds 215 for a stroker Olds built by D&D. I've run a blower on one. What you can and can't do depends a whole lot on how you'll be driving it. I've gotten by pretty well with cast pistons in my Olds 215, running 8-1/2 compression and 16 psi boost. BUT the valve springs really limit engine speed (below 5K) and the axle ratio limits time on boost (stock ratio, 24" tires) and I have blown a head gasket with this combo (multiple back to back 1/4 mile passes) and saw some signs of "nibbling" at the edge of one or two pistons. Still for regular street use it's a very strong combo. Heli-coils used in all threaded bosses is a very good idea if you want good durability. Those CC springs should let you get upwards of 6 grand, but I broke a stock Buick cast piston skirt by winding to 7 grand too many times. (it was a LOT though) Piston choices are still somewhat limited I understand. Yes, you can go over 200hp using mostly stock parts (the factory did it) and 2-300 hp in the MGB makes a phenomenal performer. A basically stock 215 is a great place to start. For more power it is relatively easy then to move up to a 300 or 340 Buick with only about a 80 lb weight penalty, or stick with the Rovers. You might want to start by nailing down just what it is you want. That will make your choices easier. Power adders like blowers and nitrous aren't the cheapest route to more power usually.

Jim



Edited 1 time(s). Last edit at 07/08/2008 12:52AM by BlownMGB-V8.


Moderator
Curtis Jacobson
Portland Oregon
(4411 posts)

Registered:
10/12/2007 02:16AM

Main British Car:
71 MGBGT, Buick 215

authors avatar
Re: engine build?
Posted by: Moderator
Date: July 08, 2008 02:10AM

Speaking of Mike Domanowski's experience with nitrous... A lot of that was documented here:
"Juiced Stroker Motor" (British V8 Newsletter, Volume 11, Issue 3)



NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: engine build?
Posted by: NixVegaGT
Date: July 08, 2008 08:24AM

I saw some numbers on the Olds vs. Buick 215 heads that showed the exhaust side on the stock Olds heads flowed marginally better and the intake was pretty close to the same. Does the rocker shaft retainer get in the way of the intake side on the Olds? I don't have those parts anymore since I finished the 5.0L build and purged. I was also thinking the extra head bolt may help for head gasket life with nitrous.

Also isn't the wedge chamber more conducive to homogenizing gasses? I thought that would work well for the nitrous as well.

I'm with Jim on the money part. The other thing to consider is parts attrition. Especially if you are trying to save up for a 5.0L build. It's expensive. I had some extra special work done to my engine but $5-6k isn't out of the ball park.

You could skip the nitrous and build a stock 215 with the tighter pistons for better compression. Get the engine well balanced and blueprint all the parts. That's good for a little extra right there and the engine will last a lot longer. Then move to those new springs Jim's talking about and put some cam into it. FUN!

OH… the 300 heads will fit the 3.5" bore. It's an old school performance upgrade. The problem I have with it is that the chambers are pretty big and are 3.7" wide so there is some overhang there. I just don't like it. IMO.


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5833 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: engine build?
Posted by: BlownMGB-V8
Date: July 08, 2008 12:39PM

Nick makes some really good points. My first 215 was a built Buick with a hot cam, big carb (600 Holley) equal length headers and about 240 hp, and like I said, I treated it like it had a 7 grand redline. I probably got 20-30K miles out of it before the factory stock 10(-1/4?):1 pistons gave out which is surprising considering the way I abused that motor. It was an absolute blast to drive.

I do think the Olds motor has some advantages for forced induction or nitrous and those new springs should negate much of the advantage the Buick heads have. You just can't get as good of flow if you can't open and close the valves. A lot has been said about the extra bolt getting in the way of the intake port, but I don't know if that's only because it limits the room for porting or what. I do know without good springs being available it didn't matter anyway and all stock springs have sagged so until now it was a moot point.

Also, be aware that there are new things on the horizon. Should TA Performance decide to make the early Buick heads they will be as good as anything available for any engine, and should be able to use the Olds head bolt pattern, or bolt to any SBB block including the 340 and 350. Also the Buick 3800 V6 is a good choice and TAP based engines have made as much as 1700 hp in twin turbo configuration. Think Buick Grand National. And no, that 1700 was not a typo.

It makes a big difference which Olds heads you have also, 2 or 4 bbl.

Jim


NixVegaGT
Nicolas Wiederhold
Minneapolis, MN
(659 posts)

Registered:
10/16/2007 05:30AM

Main British Car:
'73 Vega GT 4.9L Rover/Buick Stroker

authors avatar
Re: engine build?
Posted by: NixVegaGT
Date: July 08, 2008 09:50PM

OH I forgot to ask you, Jim. There is a lot of talk about the rocker shafts breaking at 7k+ rpm. Hearing about all this made me buy the rocker shaft gussets D&D sells for the ends. Did you have any problems like this?


BlownMGB-V8
Jim Blackwood
9406 Gunpowder Rd., Florence, KY 41042
(5833 posts)

Registered:
10/23/2007 12:59PM

Main British Car:
1971 MGB Blown,Injected,Intercooled Buick 340/AA80E/JagIRS

authors avatar
Re: engine build?
Posted by: BlownMGB-V8
Date: July 09, 2008 09:55AM

Not with the Buick heads but the Olds shafts have bigger bolt holes and aren't as strong. The only incidents of shaft breakage I've dealt with involved coil bind.

Jim


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