Problem with a 4.1 build

[boostmaster]

Been running a 4.1 for 1 year now running head studs. Didn't radius the first few threads of the block. I have had the head off at least 2 other times and never saw any damage. I suffered some major detonation that blew a piston (hyper) and had some custom forged made. It wasn't until I broke the engine down to replace the pistons that I discovered the dredded hair line cracks in 2 of the cylinders. 1 on each deck. It doesn't look like they go below the surface and I was wondering if there was any thing I could do to save the block. Maybe drill down a few threads or have the cracks welded ? Or just run it till it breaks. I'm open to all suggestions.

 

[JC Turbo]

Don't know if that can be fixed or not. If not I have two 4.1 blocks for sale if all else fails.

 

[boostingbuick]

If the cracks go from the head bolt hole to a water passage then I would say that its common. I have had two engines and both have cracks. I still own both and one is in my car now. Mine has only one and have not had any issues with the crack. I used some teflon with I installed the head studs.

 

[boostmaster]

4.1

If the cracks go from the head bolt hole to a water passage then I would say that its common. I have had two engines and both have cracks. I still own both and one is in my car now. Mine has only one and have not had any issues with the crack. I used some teflon with I installed the head studs.

Yeah but how much boost are you running and how much power are you making.

 

[sixgun86gn]

Yeah but how much boost are you running and how much power are you making.

Looking at his sig,probably alot.

 

[boostmaster]

Looking at his sig,probably alot.

Yeah but don't like to deal with speculation, need to hear it from the horses mouth.

 

[JayC]

Pretty common with 4.1s. Most of us discovered this in the early 90s as the 4.1 seemed like a cheap and reasonable upgrade but if you put any power into them, the deck cracks.

 

[boostmaster]

Pretty common with 4.1s. Most of us discovered this in the early 90s as the 4.1 seemed like a cheap and reasonable upgrade but if you put any power into them, the deck cracks.

Thanks for the reply Jay but I was trying to find out if there was any first hand experiance of any catasrophic failue due to this. Any what is the breaking point. I've spent alot of dollars on custom pistons and such that I can't use on any other engine and would like to get some use of them even if a little. Don't want to keep replacing engines and I can't afford a stage motor.

 

[JayC]

I think the breaking point is lower 11s.

You might want to talk to Lonnie Diers.. I know he did some crazy stuff with some production 4.1 blocks trying to get them to live.

Might be worth a call to Weber Racing as well. They have some really unique ideas on strengthing blocks.

 

[JC Turbo]

I was just speaking to Weber Racing about the 4.1's. He is adapting them for the additional head bolts that the stage heads are equipped with. He also has some really good tricks on how to make the block stronger with less flex.

 

[boostingbuick]

Well. I will be at norwalk with the car. I will not take off my head but my mouth can tell you its there. Not being smart, just saying its there. I will run it hard there. Looking to prove the 4.1 is a good motor. And high tens with pump gas tells me I am making some power. And thats with air and the spare tire and jack in the trunk, all the sound deading in the car and its all steel. They spool faster and pull harder.

 

[boostingbuick]

And here is what is not in my sig.

1984 484 block, 10/10 crank, je pistons, 218/212 roller cam, double roller tc, GN-r heads with t&d 1.60 rockers, fully studed,ported intake, 83's. And the turbo is a 4 bolt with ATR headers.

And I left off the foot brake. I bought a trans brake over the winter. So I plan to run faster.

I however have no cage. I have reached the platform of either stop at this power level or cage it. But I know that will change the car forever. If anyone has anymore questions I will try to help and be honest. I feel it's better to spend money once on good parts and not get something you don't need.

 

[87GN_70GS]

Someone used to make a lifter valley girdle that was used to strengthen the 4.1's open lifter valley.

 

[sixgun86gn]

Someone used to make a lifter valley girdle that was used to strengthen the 4.1's open lifter valley.

Not really needed,if you take a die grinder and clean all the casting flash and sharp edges on the lifter vally.That goes a long way toward keeping cracks from starting.

Drilling extra holes to bolt a girdle in a lifter valley kind of defeats the purpose IMO.

 

[bison]

Not really needed,if you take a die grinder and clean all the casting flash and sharp edges on the lifter vally.That goes a long way toward keeping cracks from starting.

Drilling extra holes to bolt a girdle in a lifter valley kind of defeats the purpose IMO.

Especially when the main webbing and deck will fail first.

 

[wbrophy]

And here is what is not in my sig.

1984 484 block, 10/10 crank, je pistons, 218/212 roller cam, double roller tc, GN-r heads with t&d 1.60 rockers, fully studed,ported intake, 83's. And the turbo is a 4 bolt with ATR headers.
If anyone has anymore questions I will try to help and be honest.

What boost are you running with this engine? What's your best 60 ft. and 1/4 to date?

 

[boostingbuick]

1.86 60ft - 10.98 1/4 with a 128 mph. on pump gas. 20 psi. I have had 110 in it on the street and have run boost as high as 24 psi.

 

[dlafont]

And here is what is not in my sig.

1984 484 block, 10/10 crank, je pistons, 218/212 roller cam, double roller tc, GN-r heads with t&d 1.60 rockers, fully studed,ported intake, 83's. And the turbo is a 4 bolt with ATR headers.

And I left off the foot brake. I bought a trans brake over the winter. So I plan to run faster.

I however have no cage. I have reached the platform of either stop at this power level or cage it. But I know that will change the car forever. If anyone has anymore questions I will try to help and be honest. I feel it's better to spend money once on good parts and not get something you don't need.

Hello,

I just purchased a 4.1 engine from a moderator on the turbobuicks.com site that used it in his hybrid setup (RX7 I think). He's said that he went 10.13 with this in his car @ 3000lbs. This works out to about 580RWHP. I wanted to improve the setup a bit with a roller setup.

I noticed that you are running a roller cam and roller rocker setup. Can you send me a build list for the roller cam and roller rocker setup?

I also really don't like the hypers in this build either. I would like to replace with custom JE pistons. Can you tell me how you ordered the customs? What specs did you give to build the customs?

Can you tell me what your CR is on the customs?

Sorry for all the questions but it's nice to see somebody get aggresive with the 4.1 and see whats possible with the extra cubes. Thats what I want to do .

Here is a link to a 10.4 soft launch pass with this engine for amusement.

http://www.turbobuicks.com/members/scottiegnz/10_24.wmv

Don

 

[boostingbuick]

Sure. I have the comp cams 218/212 roller cam with speed pro hydro lifters. I run a standard roller cam buttom. Takes some time to shim. Trend pushrods and a set of t&d shaft mounted rockers.

You need to find out if it needs bored. Then call JE pistons and tell them what you need. They will guide you through. 8.5 comp.

Now JE takes 8 weeks to get and cost me $759 for the set. Now I have full floating stock rods to go with the pistons. Most machine shops can take care of that.

However, now that they have the stroker kit for the 109 block, I would say that it maybe cheaper to go that route.

 

[dlafont]

Thanks,

Regarding the stroker kits for the 109... Don't you need custom pistons to use in the 4.1 anyways?

Anybody know of somebody that has stroked a non Stage 2 4.1? Anybody have any results on performance for a stroked 4.1 yet?

Don