GM 153ci vs. GM 181ci are they the same block..

[nitrosteve]

The reason I ask if they are the same block etc. is there are performance cams for the 153ci from comp cams but none for the 181ci. Here is a link to the iron duke cams 153ci the 260 even calls for a a marine application. http://www.compcams.com/catalog/046_047.html
I could see getting 15-20 hp just from a cam swap and improved torque over stock. Just for fun here is a 153 ci with 400hp n/a built by KRP

 

[Bondo]

Re: GM 153ci vs. GM 181ci are they the same block..

Ayuh,... Externally they're the same,... Internally they're Not...

Call Compcams,+ ask Them...

 

[TilliamWe]

Re: GM 153ci vs. GM 181ci are they the same block..

... Here is a link to the iron duke cams 153ci...

The 153 and 181 Chevy engines are as Bond-o explains. However, I want to caution you, "Iron Duke" is NOT a 153cid Chevy engine. It is a Pontiac engine, and it's COMPLETELY different than the Chevy engines used in the Chevy II and Mercruiser engines.

 

[nitrosteve]

Re: GM 153ci vs. GM 181ci are they the same block..

The 153 and 181 Chevy engines are as Bond-o explains. However, I want to caution you, "Iron Duke" is NOT a 153cid Chevy engine. It is a Pontiac engine, and it's COMPLETELY different than the Chevy engines used in the Chevy II and Mercruiser engines.

Yeah after reading up on this alittle more I realized the Iron Duke is a 151 ci Pontiac but the compcam sheet is for the 153 ci. I tried to call comp cams but no one answered there 1800 number. Guys are building the 153 ci in s10's and Jeeps and interestingly enough a popular swap for them is to go to the marine 181 ci they say it has a crank that can handle 4-500 hp. Imagine a 3.0 in a boat with 4-500 hp N/A. Im considering over next winter getting a custom ground cam and adding a 4 barrel be it a small 4 barrel 600cfm or a 500 2 barrel. I figure this would add 40 hp and put it close to the 4.3 hp. And to think someone told me there were no performance upgrades for the 3.0l Where there's a will there's a way.
But going back to my question I realize the internals are different but can you swap the cams? I know you can swap the crank with very little grinding for clearance. I know you can swap the dist. which makes me think the cams would be swappable.

 

[Bondo]

Re: GM 153ci vs. GM 181ci are they the same block..

Imagine a 3.0 in a boat with 4-500 hp N/A.

Ayuh,.. The Problem with that is, it Can't be done at the Useable rpm range of a Marine Motor...

 

[JustJason]

Re: GM 153ci vs. GM 181ci are they the same block..

hmmm... that doesn't look like a 2.5L. The manifold is on the wrong side.

 

[nitrosteve]

Re: GM 153ci vs. GM 181ci are they the same block..

Ayuh,.. The Problem with that is, it Can't be done at the Useable rpm range of a Marine Motor...

I guess 7-8000 rpm would put the peak torque curve up in the rpm range. I would agree probably not the best option but fun to think about. My real point was that the crank can handle some serious HP so there is room for improvement on the stock 3.0l there are those that think the 3.0 is already stretched at 140 hp its just not true.

 

[Bondo]

Re: GM 153ci vs. GM 181ci are they the same block..

I guess 7-8000 rpm would put the peak torque curve up in the rpm range. I would agree probably not the best option but fun to think about. My real point was that the crank can handle some serious HP so there is room for improvement on the stock 3.0l there are those that think the 3.0 is already stretched at 140 hp its just not true.

Ayuh,... At useable marine rpms, the 3.0l Is in fact Stretched to it's Limits...

Horsepower is just a # derived from measurable Torque, vs. Time...

You can go on beating yer Dead Horse, but you're not going to build a 3.0l that has a Feel-able rise in horsepower...

 

[nitrosteve]

Re: GM 153ci vs. GM 181ci are they the same block..

Ayuh,... At useable marine rpms, the 3.0l Is in fact Stretched to it's Limits...

Horsepower is just a # derived from measurable Torque, vs. Time...

You can go on beating yer Dead Horse, but you're not going to build a 3.0l that has a Feel-able rise in horsepower...

I disagree....About the dead horse. But thanks for your opinion.

So that's how horsepower is measured huh....

 

[nitrosteve]

Re: GM 153ci vs. GM 181ci are they the same block..

hmmm... that doesn't look like a 2.5L. The manifold is on the wrong side.

Good eye its actually a gm head they manufacture the blocks to except the GM style heads.

 

[zbnutcase]

Re: GM 153ci vs. GM 181ci are they the same block..

Cams are interchangable between 153&181 cid. The only difference is bore size:3.875 on 153 & 4.00 on 181. A colleague mildly built a 3.0L for a customer of his for a jet boat. Bought brand new 3.0L with the 8 port head, sent head to machine shop. Had 3 angle valve job done and fitted with Z/28 springs. Had Oregon Cam Grinders regind cam to factory 350hp 327 specs, finished it off with late Mercruiser manifold and 500cfm Holley marine carb. Runs great and it rips! It can be done for a boat, just don't get carried away. 'nutcase

 

[nitrosteve]

Re: GM 153ci vs. GM 181ci are they the same block..

Well this has been a fun exercise in realizing I am not going touch my 3.0l. The more I think about it the more I am realizing its a waste of time. After much thought and some more research I am leaning towards agreeing with Bondo. Yes I am back peddling but when the voice of reason sounds some time it takes me awhile to see the light. There really is just no feasible way to make it worth while even after I sink a grand into the shortblock and the head work and only see minimal gains at the end of the day its still a 4 cylinder. So I will save my money suck it up and wait for my new boat which will have at least a 4.3l.

 

[Bondo]

Re: GM 153ci vs. GM 181ci are they the same block..

Well this has been a fun exercise in realizing I am not going touch my 3.0l. The more I think about it the more I am realizing its a waste of time. After much thought and some more research I am leaning towards agreeing with Bondo. Yes I am back peddling but when the voice of reason sounds some time it takes me awhile to see the light. There really is just no feasible way to make it worth while even after I sink a grand into the shortblock and the head work and only see minimal gains at the end of the day its still a 4 cylinder. So I will save my money suck it up and wait for my new boat which will have at least a 4.3l.

Ayuh,... Glad I could turn the Light on for ya Steve,....

Blown is really the Only way for it to work,...

 

[rodbolt]

Re: GM 153ci vs. GM 181ci are they the same block..

and no one noticed the block in the above picture is NOT a 153 nor a 181 CID block made by GM.
the distributer is in the wrong place.
no pads for the engine mounts and no way the engine mounts will fit with that crank driven oil pump.
killer looking lil beast but it looks like its based on the 151 pontiac motor.

 

[smokeonthewater]

Re: GM 153ci vs. GM 181ci are they the same block..

and no one noticed the block in the above picture is NOT a 153 nor a 181 CID block made by GM.
the distributer is in the wrong place.
no pads for the engine mounts and no way the engine mounts will fit with that crank driven oil pump.
killer looking lil beast but it looks like its based on the 151 pontiac motor.

consider reading what everyone said before stating what no one noticed