NITROUS JUNKIE

OK the 415 is all apart....# 6 did blow a head gasket and broke a piston. I am running the JE pistons with the valve reliefs. There is very little meat on the piston between the valve reliefs and the ring land. So its time to punt the Je pistons and run something better. I have a custom set being made, I should have them in a few weeks. I have the same stroke, rods etc...in my SB2 engine and I really like the pistons and ring pack. So I will be giving them a try in my LT5.


Obviously it is not the pistons fault that the engine is broke, but I think if a problem occurs the JE design is not strong enough if there is a problem. It is a very good possibility if there was more meat between the valve relief and the ring land the piston may have survived. Tearing apart the engine the rest of it still looked new, crank and cylinders looked excellent. So it wont hurt my pocket too much!!


What I found when it came apart is the secondary on # 6 was not working. All the rest of the secondaries were working good. So if it was staying shut that may have been part of my problem. Also the wide band O2 was only on the drivers side header, next time I will be running dual wideband O2s. So I really dont know what the A/F ratio was on the passenger side. I have had some problems in the past with secondaries not working properly, but this time it bit me. I will also be checking the # 6 injectors as well as the N20 nozzle. It looks to me that it ran lean and detonated.

So now with it all apart I have many new options on the new engine. I was considering siameseing the plenum and injector housings. I was also considering pulling out the secondaries. I am very happy with the cylinder heads that the "master" Greg Vandeventer did for me but maybe there is some gains in plenum, maybe putting in big valves. Let me know what you guys think???

A26B

What are you running for cams?

BTW, Kurt Whites piston (2) broke the same way you describe. I've got some pics of them. Sure looks like its too thin under the flycut valve relief....that right where it broke.


[Modified by A26B, 9:07 PM 6/8/2004]

BiZ

I have had some re occuring problems with my secondary system in the past. Seems some of the actuators I had been getting were the poorly manufactured ones. I had to go in there for actuator replacement 3 times in a 10 month span. The last one I got was in November just before the SGC gathering. So far so good.

But I have been curious to what would happen if the secondary system failed during nitrous use. I will be watching this one. I hope all goes well with your rebuild.

NITROUS JUNKIE

Right now my car is running stock cams, I really like the driveability and I dont really think there is very much horsepower gains with the cams. I think that the cams are kind of a trade off, peaking horsepower in some places while losing it in other places. I really dont think there is enough research involved on the big LT5 cams, there is just not enough LT5s out there to have the kind of development that needs to be done for some killer cams. I have tried reground cams years ago on my car, I really was not impressed. I really like the idea of driving my car to the grocery store then running 9s later that night at the dragstrip. I think I have that combination with the auto setup and the 415. I also like to drive my beast to work everyday. So I am having a hard decision on pulling the secondaries out.


For the pistons I'll take some pics of the thin relief/ring land areas. I like to spend money on good pistons for the extra strength, the pistons I have are for sure not the way to go. One valve relief was broke and another one was pulled up only at the relief areas. The thicker areas were in great shape.
The new pistons I ordered have a killer ring pack and the rings are moved further down from the top. I never took any pics of my SB2 pistons, but when I get the new ones I'll post some pics.

Keep your opinions coming!!!! Any ideas are appreciated

taknkarevette

Im just curious as to what the cost of the pistons are?

Do you need to change the liners for the piston swap or are they the same size?

I would love to build a 415 when I get home but thats then this is know....

johnny

DDSLT5

Maybe rethink that one! The stock cams weren't even optimized for 350 cids - how could they be optimized for 415 cids?

I understand your point about driving to the grocery store etc - but that doesn't mean that cams won't make more power with your 415!

Rkreigh

the stage III cams will be worth 40-60 HP on top end with the big 415.

they are expensive and cause some tuning headaches, but they would also help with the extra exh flow from the nitrous. you might consider aarons stg II or III cams which you have it apart. the factory cams give a nice smooth idle but you are leaving some torq and ponies "on the table" with the big 415.

glad the engine wasn't hurt too bad, I was sick to hear it failed!!

good luck with the redo, keep us posted on what you decide.

nice meeting you at BG this year!! cya

NITROUS JUNKIE

I agree the big cams will make more power than the stock ones, but what I'm saying is there isnt really big gains especially when you consider the price tag of the big cams. It is easy to get better peak hp numbers on a dyno at the expense of power at other rpms. OK they say there worth 30-60 more hp with the big cams, but I would also be willing to bet that degreeing the stock cams would also be worth some big power on the 415s. Dynos can be misleading sometimes with peak hp numbers. I have had the cams pin timed as well as degreed to different specs on my 415, we for sure picked up a lot of top end degreeing them. The good thing about the 4 cam engine is the ability to change the cams relative to one another, so much better than just advancing or retarding the cam on a regular SBC. I guess it all comes down to where guys want to spend their money.

NITROUS JUNKIE

Johnny, I'm not sure what the JE slugs are going for now, the custom pistons I'm having made are going to cost $80 per hole. You will need to change the liners. A 415 is a 4 inch bore x 4.125 inch stroke and most are 5.850 inch rods. The biggest expense is in the crankshaft, you will also have to notch the block to clear that big stroke.

phrogs

I would love to build one of my ZR1's into a 415, I would do all the work but I would need someone to do the dyno tune

I figured the pistons would be a lot more costly than that

so how many 415 cranks are left??? does anyone know??

they were about $5,000 a pop last time I saw one for sale!!!





[Modified by phrogs, 6:47 PM 6/9/2004]

MrCrowley

Rod as far as the siamesed setup here are my results with the cnc head program that we have. GO to this url to see the results. http://forums.corvetteforum.com/zerothread?id=731067
My opinion there is it might help you alittle, but not enough to justify the cost, unless you have lots of cubes, and big cams. Al tried it on his car(415), and he still traps 128 without it. NOw that is real world results!

But I do think a siamesed setup will help some. People out there who dont have super maxed out ported heads that can benefit from it. But in our case it didnt. Ported 350's run from say 390-440rwhp, and that tells you all porters arent the same.

I would suggest going will the reground cams for starters as you can always sell them and get your money back. I would also do bigger vavles, and some more port work on the heads, plenum, and Ih's. Make sure your heads flow 330+cfm before the larger valves. Let me know if you need help with any of this stuff too.

Try that on your next buildup and see what you get!

Mike





[Modified by MrCrowley, 7:10 PM 6/9/2004]

NITROUS JUNKIE

Johnny, I think there will be plenty of 415 cranks available for as long as I can see. Who wouldnt produce them for 5k? I know there a couple of people doing them, but I have heard the Jerry Crews cranks are the best. As for the piston costs, most pistons nowadays are custom. So regular SBC or LT5 it doesnt really matter.

Rkreigh

rod I do agree that on a nitrous engine the cost of the cams probably doesn't pan out, 3200 + for 40-60 HP is nothing when you can just spray it a bit more way cheaper.

I would ditch the secondaries. the loss of low end torq is insignificant with a 415 with the auto, less headache, less things to fail, and I believe now tuners can step up with a calibration that will really do well even without them.

the big inch LT5s have tendancy to surge transitioning, and I really don't think this crutch for low end torq will be much of an issue for you.

I was talking to Jim and Corey about this, I would ask their advice.

I also thing that getting the pistons strong enough with the 415 crank maybe a bit of a challenge. Kurt has decided to go 368, park the ring lands further down, and just make more power with the spray. sure you loose so torq off the bottle, but who cares?? you can make all the power you need with the squeeze and get the combination to live by making the piston stronger and reducing the side angle load.

let me know if you need a stock crank, I have a honey out of my 95 I'll ship you cheap, it's perfect.

I also have a crank with one bad journal. I have been tempted to run an offset grind crank, with a smaller big end rod with smaller bearings. it would be lighter, less drag, and be pretty trick. alot of the comp guys do this with pretty good results!!

this go around I'm sure you are pretty far along with the 415 route, just things to consider for the future. with turbos and nitrous, you might not need all that expensive stroke, the bottle can make plenty of power!!

NITROUS JUNKIE

Thanks for your input Ron....I have the new pistons for the 415 with the ringlands moved further down more than what everbody is running now. YES it can be done very easily. So as far as the piston strength issue I have it solved.
I agree with you though the 368 would be a good one to spray big. I had a 368 one time, there is nothing quite like the 415. I like the idea of being a hardcore Nitrous Junkie and being able to take the lines off the bottle and still punk out most cars out there. I guess I want it all.....im pretty sure I can make it live Taking the secondaries out sounds like a great idea, the secondaries sure can bite you. It looks like I will have to find a real good computer guy.

MrCrowley

I am colaborating with a customer doing a 415 with a 4L80e like you did. But he has stage 2 cams, my oversize valves(bigger than all other tunners), all out intake porting with the cnc head program I got. It will be very nasty! The bigger valves I use will almost be the equivalent of stage 3 cams. I cant wait for the outcome, but it will be pretty sweet. We are expecting a conservative 535rwhp with the 4L80E naturaly aspirated. I do wish you luck on your project, and hope we all can learn from one another to make the next situation better!

Mike

Rkreigh

rod,

love to hear more about the pistons, they sound like they will really help. I would also like to time the stock cams to favor the exh a bit more, I'm sure it will help.

glad the damage wasn't too bad, I know you want to get that beast back on the road again.

if you get corey's phone number, please email me, I need to talk tuning with him. the 390 runs great but I am still chasing a bit of a surge problem at around 2500 rpms.

thanks!!

NITROUS JUNKIE

Mike...Good luck with the project. How many 415 have you built? Im just curious how you are estimating the hp levels? I have no idea what mine is putting out. And good luck with the auto, it is a hard deal to get it right.
Im still interested in doing turnkey setups for the auto, it is proven and very reliable the way I have it done. It ran 10.60s with this setup, stock cams and valves. 9s are for sure do able. It was quite a bit faster than Berts 6 speed car with a 415.

BERTZR1

Quote: It was quite a bit faster than Berts 6 speed car with a 415.

Put the drag radials on loose the front runners and the juice then come talk to me about being fast.




[Modified by BERTZR1, 1:22 AM 6/11/2004]

MrCrowley

Here is how I get those hp numbers. Take 438rwhp and divide it by 350cid, and you get a rwhp/cid ratio which is 1.25. Now take 1.25 and multiply it by 415 and you get 519. Now bear in mind that is with a 6speed. A auto car will loose power to operate the tranny. Now that 519rwhp for a 415 is right on track if you take Alberts engine into consideration.

Now add in bigger valves, new seats, stage 2 cams, and I think that will put us on this 415 right where I predict it to be. It might even be alittle bit more! The car should trap 132-133 all MOTOR with the auto.

As far as whos parts I use in my 415's. Well I use my own. There are more than 2 cnc machines(Jerry crews, and Sunny Bryant) out there to build a stroker crank. And then there are thousands of machinists that can operate it. With that in mind its not rocket science to build this engine. Having all the machine equipment to do it makes it very easy to take it to the next level. Its actually harder to siamese a plenum and IH set, than it is to build a lt5 shortblock!




[Modified by MrCrowley, 12:12 AM 6/11/2004]

ZR1Pete

[QUOTE]Quote: It was quite a bit faster than Berts 6 speed car with a 415.

Put the drag radials on loose the front runners and the juice then come talk to me about being fast.
QUOTE]



Also would like to add, that the auto gives up 1-2MPH over the M6.
I would think Rods car runs 126MPH street trim (sway bars connected with stock front tires on DR's)add the front runners and runs 127-128MPH.
Al's car will run 10's @ over 129-130MPH with front runners on motor,hell it ran 11.20's on DR's on street trim with a fried clutch at BG, the car would have run 10's that night if the clutch held up.


[Modified by ZR1Pete, 2:11 AM 6/11/2004]