engine build questions????

[95whiteGSX]

okay this is for all the engine guru's out there, i got a bare 7 bolt that is bored .020, i have pistons that are for .040 bore. Is it worth it to bore my block to the .040 or just buy some new .020 bore pistons? and is there really any gains from the bore?

as far as supporting mods for the engine, its gonna have a built head with kelford 272's, springs an retainers. its gonna be runnning a Greddy 18g, ported exhaust mani + 02 housing, full 3in TBE, intercooler kit, 1050cc injectors, and walbro 255

any input would be nice
Thanks
Frank

 

[My1GLaser]

There is no real measurable HP gain in boring it to .040 over. But if you don't wanna drop the cash on .020" pistons then bore it to match what you have. Keep in mind that you won't have as many rebuilds left on that block if you go to .040" over. Most don't recommend going more than .060 over on a 4G63 depending on the boost and HP you are running.

Make sure you get good beehive springs to match those Kelfords. There is plenty of info on the forum about it.

Not sure the 18G is the best turbo to match with those Kelfords. Personally, I would want something that wouldn't choke out in the upper rpms if I had those cams. I'm sure it will still be a good build, but you won't be able to maximize the lift and duration that they offer.

 

[95whiteGSX]

okay i was just making sure it would be worth it to keep the .040's an just bore the block to match them, i know they dont recomend anything more than .060 and i dont plan on going even that big, and i'll also have my stock block incase something happens.

I'll deff be doing the beehive springs but now that I'm questions the kelfords i dont know what to do

okay so what would be the cams you would go with? I have a set of BC 264's but i had them in my old evo 8 and i didnt like them, STM recomended the kelfords to me just trying to get some more imput on what i can do since i dont want to like you said choke in the high rpms

 

[Mitsubishiown]

Just curious. If you run 272 cams and you have a proper tune the car will still be fine as a dd even if you are mainly street driving (lower rpms)? I am not to knowledgeable about how engines work.

 

[95whiteGSX]

after the BC's in my evo i went to a set of HKS 272's make 330awhp and 325awtq. after it was tuned regular DD, stop and go traffic, hills ECT... it was fine i didnt have any problem at all maybe just a lil more gas from a dead stop, im not really sure how to explain it but how it was explained to me is that cams more or less change where your power band starts and it allows your rpms to go higher as well not really sure if im correct on that but thats what i know or think i know?


if im wrong please done bash me just correct me
Thanks

 

[My1GLaser]

Generally higher lift, longer duration cams move the powerband to the right. ie; higher in the rpm band and you tend to lose a little low and/or mid range power. The Kelfords tend to make power everywhere, from what I have read. An 18g starts to choke above 7k-7.5k rpms.

I killed my 18g in about 2 months trying to run 30 psi. I only have HKS 272s which are 10.3 mm & 10mm lift. Kelford 272s are 11mm which is huge. I believe the duration is quite a bit more as well.

Don't get me wrong, they are a great cam and I wish I had them now with my HX-35. If you have the money and don't mind the extra effort in setting up the head to properly run these cams, then go for it.

It really depends on your goals. Drag car, quick spooling street car, autox, 300whp, 400whp, 500 whp, etc...Its more about properly matching mods to maximize the output while working within your budget and shooting for the goal you have for the car and leaving some room to grow as time progresses. There are trade offs all along the way...

I started 5 years a go with a 14b at 18 psi as a break-in turbo. I am currently running an HX-35 at 35 psi and over 500 whp. Same motor setup, 4th tranny You get used to how the HP feels and you constantly need more. My friends thought I was nuts when they rode in the car and I told them that 400whp didn't feel fast anymore

So are you trying to get a little more top end? What rpm do you want to take your car to? I take it you already have the turbo...

 

[95whiteGSX]

Thanks for explaining that better for me,

as far as goals go for the car im just looking for a 400hp street car that i can take to the strip sometimes and beat up on some honda's ya know. im trying to get a litlle hight rpm since its auto and yes i have the turbo already, my wife got it brand new from greddy shipped w install kit for 600 so for the price im happy with it and like you said room to grow so i can go bigger than the the 18g and as far as the cams go i may go back to the HKS 272's myself i had em in my 8 and loved them to death

 

[My1GLaser]

You shouldn't have any problem getting into the mid to low 11s with 400whp and an auto. I ran 11.8 on my 18g in a full weight 5 speed 1g AWD.

Stock converter in the auto? Have you tracked it before? You're gonna need a quick spooling turbo to get a good launch off the line with the stock converter. Have you ever foot braked to see how much boost you can make before it overpowers the brakes?

Personally, I would spend the $6-700 you were gonna spend on the Kelfords and look into a Sinister Speed 10" converter. It will be a lot more fun on the street with a "looser" converter also.

I have a little larger turbo, and am switching to auto soon and the torque converter is my main consideration right now. I know this gets a little off topic as far as the engine build goes, but it is a factor for the build overall.

 

[BogusSVO]

Here is a good thread on some cams and how they worked out...

http://www.dsmtuners.com/forums/cyl...est-delta-hks-272-delta-k272-bc-272-cams.html

After you read that one... look at theses...

http://www.dsmtuners.com/forums/cyl...y-cam-selections-gsc-s2-vs-kelford-272-a.html

http://www.dsmtuners.com/forums/cyl...ice-my-setup-future-setup-looking-advice.html

Now when getting the beehives Look at the GSC Part # 5041, they are a nice set up, I just installed a set on a head, and the fitment if flawless, no fancy spring seats needed.

 

[GalantStroker]

I'm just curious why the OP is talking about building a 7 bolt, you can get a donor 6 for pretty cheap and the conversion isn't really that hard. In and of itself there's nothing wrong with the 7 bolt motor but the kind of power he's talking accompanied by the reliability he wants, i'm just not sure he's going to get that out of the 7.

 

[bryanwheat]

I'm just curious why the OP is talking about building a 7 bolt, you can get a donor 6 for pretty cheap and the conversion isn't really that hard. In and of itself there's nothing wrong with the 7 bolt motor but the kind of power he's talking accompanied by the reliability he wants, i'm just not sure he's going to get that out of the 7.

A 7 bolt with a set of forged rods and pistons is theoretically stronger than a 6 bolt with the same. The 7 bolt is a lot more stout in the main cap area.

 

[BogusSVO]

Finding a 6 bolt is getting harder and harder as the years go on. Plus on a proper built 7 bolt 400 shpuld not be all that hard to do.

 

[95whiteGSX]

Thanks bogas I'll look at those when I get outta work

Galantstroket
I'm not build a 6 bolt because I got the 7 bolt w pistons and a full head for 200 I'm not gonna go out an spend money on a 6 bolt when I can make just as much power on the 7 bolt I have an god forbid that something happens to my 7 bolt I have another one that I'll be pulling out

 

[GalantStroker]

A 7 bolt with a set of forged rods and pistons is theoretically stronger than a 6 bolt with the same. The 7 bolt is a lot more stout in the main cap area.

The only reason anyone would have reason to believe the 7 bolt's main area is stronger is because it's a girdle vs. individual caps. I've put together both types of engines and the 7 bolt was a rebuild because it crankwalked (go figure) but regardless of the strength of the main caps (which is really pretty irrelevant when you use good hardware to put them in) the 7 bolt's thrust bearing setup in it's stock form is not so great. And the 7 bolt rods are always going to be skinnier than the 6 unless you do some serious modification to the crank to make them fit a bigger rod. What do you suppose is more likely to fail, the main bearing caps that dont move? or the rod caps that do?

When you talk about built motors, compare the 6 bolt built to the 7 bolt built with components that actually fit in their stock form and tell me which is the one you'd pick.

Finding a 6 bolt is getting harder and harder as the years go on. Plus on a proper built 7 bolt 400 shpuld not be all that hard to do.

I do agree with this post, maybe 6 bolts aren't as common as they once were, but they are still out there. My buddy picked up a donor 6 bolt longblock for $300 a couple months ago when his 7 bolt took a crap.

I'm not saying it can't be done, but if you have to spend the money anyway (which in hindsight it seems like the OP is trying to build on a budget here) the 6 bolt is a better platform to start with if you're not willing to spend the money to make a 7 bolt reliable.

Again, this is all my opinion, but it is based on experience with both motors.

Thanks bogas I'll look at those when I get outta work

Galantstroket
I'm not build a 6 bolt because I got the 7 bolt w pistons and a full head for 200 I'm not gonna go out an spend money on a 6 bolt when I can make just as much power on the 7 bolt I have an god forbid that something happens to my 7 bolt I have another one that I'll be pulling out

6 bolt short blocks aren't really that expensive, and you can still use the 7 bolt head. I just did one of these builds. If you're not willing to spend money for rods and good bearings, 6 bolt is a better starting point. If you're going to spend the money to bore your cylinders another .020" over, it's probably going to cost you between $130-$160, half the price of a 6 bolt block. Then you still have to put everything else together.... so you tell me what's cheaper (and more reliable) in the long run. Not trying to be a dick here but i know how much it costs to put these motors together and i think you're not factoring in all the little nickel and dime crap that kills your budget build.

 

[95whiteGSX]

I understand what your saying galant, I already have a forged crank and rods . I don't plan on going cheap with anything inside the motor I was just asking simply if I should spend the money in new pistons or on boring the block, and I'm just gonna bore the block not really a big deal, I don't know how u got started on 6 bolts and it's not really a big deal. I have a 7 bolt that I'm building and will be built the right way

 

[GalantStroker]

I understand what your saying galant, I already have a forged crank and rods . I don't plan on going cheap with anything inside the motor I was just asking simply if I should spend the money in new pistons or on boring the block, and I'm just gonna bore the block not really a big deal, I don't know how u got started on 6 bolts and it's not really a big deal. I have a 7 bolt that I'm building and will be built the right way

Lol okay then. You didn't list those among your assets in the original post. In your reply to my original post you said you have a 7 bolt block with pistons, that implies you're planning to run a stock crank and rod. If you already have rods and a crank then for what you're looking for in power that should be alright. Just dont cheap out on the bearings you buy, they're key in a good build. To answer your original question though, boring to .040" to match pistons, i'm not sure i would want to go that big (to be honest). I know guys on here have said .060" is okay to do on the 4g63 because it's cast iron but I think for reliability's sake i would not want to bore my motor over .030". That's just my personal opinion though, take it for what it's worth, but personally if you're willing to spend the money to do this right I would just buy pistons that fit.

 

[bryanwheat]

the 7 bolt's thrust bearing setup in it's stock form is not so great. And the 7 bolt rods are always going to be skinnier than the 6 unless you do some serious modification to the crank to make them fit a bigger rod.

The thrust setup on a 92-97 7 bolt is identical to a 6 bolt. What is so bad about it? I assume that you know what causes them to fail and have it down to a science fixing them? You mention that they are bad in stock form, what other option is available? You do know that the 98+ 7 bolts use a different thrust setup that doesn't have issues like the 97 and down right? As for rods, aftermarket rods are around 300 bucks and will handle 700+ horsepower. Evo rods will handle 500+ with arp's and can be bought for 50-75 for the set. You can also narrow a set of 6 bolt rods to run in a 7 bolt as well. The big end of the rod isn't the weak point, the weak point if the area between the 2 holes. Stock 7 bolt rods will commonly bend in this area.

 

[95whiteGSX]

Sorry I forgot to put that I wasn't really thinking about it at the time, the blocks already to the machine shop it had to get cleaned either way and they arent even charging me for the bore to .040 since the engine has already been there once to get bored to the .020 that it's at now. And yes I planned on going with some good bearings since I don't wanna have the crank walk on me .

 

[bryanwheat]

Sorry I forgot to put that I wasn't really thinking about it at the time, the blocks already to the machine shop it had to get cleaned either way and they arent even charging me for the bore to .040 since the engine has already been there once to get bored to the .020 that it's at now. And yes I planned on going with some good bearings since I don't wanna have the crank walk on me .

It would be a REAL GOOD idea to either remove and block off the oil squirters or replace them with new ones. They have been proven to open prematurely when they get some mileage on them.

 

[95whiteGSX]

Alright, anything else I should consider while I'm at it?

 

[GalantStroker]

The thrust setup on a 92-97 7 bolt is identical to a 6 bolt. What is so bad about it? I assume that you know what causes them to fail and have it down to a science fixing them? You mention that they are bad in stock form, what other option is available? You do know that the 98+ 7 bolts use a different thrust setup that doesn't have issues like the 97 and down right? As for rods, aftermarket rods are around 300 bucks and will handle 700+ horsepower. Evo rods will handle 500+ with arp's and can be bought for 50-75 for the set. You can also narrow a set of 6 bolt rods to run in a 7 bolt as well. The big end of the rod isn't the weak point, the weak point if the area between the 2 holes. Stock 7 bolt rods will commonly bend in this area.

No, it's not. The 92-94 4g63T's were still 6 bolt motors. only the non-turbo cars came with a 7 bolt until 95. In 95 they started using the washers in the turbo cars. There really are plenty of aftermarket thrust washers available for the 2g dsms... although i can't comment as to whether or not they work because both of the crankwalked 7 bolt cars owners i know converted to a 6 bolt when their 7 bolt went bye bye so they never had the problem after that.

As to the cause of failure, i can only speculate to the real cause, but the thrust bearing/washer is the only components whose failure would cause the crank to shift in the car and make it eat the other bearings. It's the only component in the bottom of the motor that actually has direct lateral contact with a crankshaft surface. I do, however, suspect that this problem is less common in the automatic cars because you dont have to apply force to the crank for it to shift gears, unlike the manual cars.

Anyone can say that "oh, a 97 and newer car has a better built 7 bolt and it doesnt have the same problem." Wrong. My buddy's 98 gsx crankwalked not even 6 months ago. Before that another friend of mine from back home has a 95 talon that also crankwalked. So obviously the problem is still there, even if it's not as prevalent in the later 2g's (which you can say it's not all you want, but the fact of the matter is only a handful of dsm owners actually post on forums so noone knows the actual rate of failure and not even all the ones that do post on forums actually say their motor ate itself).

Now, with respect to the rods, yes, you can buy aftermarket rods, but I wasn't talking about aftermarket rods, i was talking about the stock ones. You'll note that if you read my reply to the OP after he said he already had rods and a crank. Evo rods were built a little better because the evo was meant to be a rally car. 6 bolt rods can be machined to fit, I never said they couldn't, but, it's not going to be any cheaper than machining the crank to make a stock 6 bolt rod fit. Either way you're removing material from a rotating or moving part, and why would you do that when you could just have parts that fit to begin with and have even less chance of reducing their integrity?

In any case, we were talking about cost originally which is why i even brought up the 6 bolt to begin with, because, as a starting point the 6 bolt is in an of itself strong enough to take the power he wants to make and be reliable. Sure he might want to replace bearings and seals, but the original components are solid. But since he was talking about a built motor, i would take a 6 bolt to start with over a 7 any day since the cost of building each is the same if you're starting from scratch.

Since he has the block already, already has bottom end parts, there's no reason not to run what he has until he needs to build another motor. If that happens, maybe he will consider running a 6 bolt at that time.

It would be a REAL GOOD idea to either remove and block off the oil squirters or replace them with new ones. They have been proven to open prematurely when they get some mileage on them.

Does the 1st gen 7 bolt even have oil squirters? because the 2nd gen one oils through the rod instead of using the squirters like the 6 bolt.

 

[bryanwheat]

No, it's not. The 92-94 4g63T's were still 6 bolt motors. only the non-turbo cars came with a 7 bolt until 95. In 95 they started using the washers in the turbo cars.


Does the 1st gen 7 bolt even have oil squirters? because the 2nd gen one oils through the rod instead of using the squirters like the 6 bolt.

You are wrong. 90 to early 92 are 6 bolt's turbo and non turbo. Late 92-97 are 7 bolts with the thrust bearing and main bearing attached to each other. 98-99 use a thrust bearing that is not attached from the main bearing.

The 2g engine DO not oil the piston thru the rod. They have an oil jet in the main journal casting. The hole in the rod is for wrist pin lubrication. 1g 7 bolts use the same design oil squirter as a 6 bolt.

I don't disagree that it would be a better idea to build a stock 6 bolt, i am well aware that they are stronger in stock form.

IT is possible for any engine to crank walk, 6 bolts do it from time to time. Any engine ever made can have this happen. It is many many times less likely with a 98+ block.

 

[GalantStroker]

The 2g engine DO not oil the piston thru the rod. They have an oil jet in the main journal casting. The hole in the rod is for wrist pin lubrication. 1g 7 bolts use the same design oil squirter as a 6 bolt.

This is actually what i meant to say. Sorry i know that was confusing.

I have never seen a 1g with a 7 bolt. I guess it doesn't mean they dont exist, i know they come with a 7 bolt if it is the non-turbo, but i've never seen a turbo 7-bolt in one that came like that from the factory. I'm speaking purely from experience here, i don't typically rely on forums for knowledge.

Anyway, we're sort of getting off topic. At least we agree on a majority of the points that were made.

 

[95whiteGSX]

its all good i dont mind the getting off topic as long as it has to do with engine and and building it and its good information to know about all that stuff ya'll been fighting about