Upgrades for 402 LS

[David Pozzi]

I bought a 402 LS from some guy named Steve Rupp, he says it was only driven to church on sundays...

But seriously, here's his build info and I need a little advice on perking it up.


LS2 block
AFR 205 custom ported heads
Comp hardened push rods
Bushed GM rockers (CME)
Lunati Pro Series Crank (4" stroke and 24x reluctor wheel)
Lunati H-beam rods
Weisco Flow-dome forged pistons (about 11.1:1)
Fast 90mm intake
All ARP bolts, head studs, main bolts
Includes FAST injectors/Fuel logs and sensors
Canton pan.

about 3,000 miles on the engine.

Runs REAL hard and made 488 rwhp and 475 rwtq last time it was chassis dynoed.

You can read about the build here... all the machine work was first class and it's a hard running engine.

Read the build story here:
http://www.camaroperformers.com/cama...ade/index.html (http://www.camaroperformers.com/camaro-tech/engine/camp-0902-1968-chevy-camaro-engine-upgrade/index.html)

It's a really good engine but I realized a couple of things.
1. The 205 AFR heads were selected back when the engine displacement was 6.2L I think this is hurting top end power now that it's a 402.

2. There are now better heads around BUT I don't want to hurt low end torque, that's where this engine shines right now.

Is there a better head and intake setup that would still make good torque but boost top end? Step one might be to use the AFR 225's, but then there's the LS3 type...:idea:
Thanks, David

[CarlC]

8 psi make any head flow better. ;-)

[John Wright]

8 psi make any head flow better. ;-)LOL...this is true

[Steve1968LS2]

I bought a 402 LS from some guy named Steve Rupp, he says it was only driven to church on sundays...

But seriously, here's his build info and I need a little advice on perking it up.



It's a really good engine but I realized a couple of things.
1. The 205 AFR heads were selected back when the engine displacement was 6.2L I think this is hurting top end power now that it's a 402.

2. There are now better heads around BUT I don't want to hurt low end torque, that's where this engine shines right now.

Is there a better head and intake setup that would still make good torque but boost top end? Step one might be to use the AFR 225's, but then there's the LS3 type...:idea:
Thanks, David

The problem with that Rupp guy is that he would any joker drive his car... guys like you! lol

When we dyno tested the engine the volumetric efficiencies were good so I don't think the engine was running out of air. Nonetheless, if you put on some larger heads you would see an increase in top end power but would most likely loose some low end torque. In other words it might just shift the curve around. I will call Mamo and ask he what he thinks.

And to clarify the 205 were custom massaged by Tony Mamo at AFR, so they flow better than a standard set of 205s.

If you want more steam I would simply bump up the cam a bit. Right now it's a 238/240 and is pretty darn mellow. I also think the LSA is 113 or so. Moving that to a 112 (plus 4) and upping the durration will give you some more power. Plus the 112+4 would be good for low and midrange torque. I would have to be custom ground since the cam in the car is the biggest "off the shelf one" but I connections.

Another thing that would help would be trading out the FAST 90mm intake for thier brand new 102mm cathedral port intake. If you did this then you would also want Mike Norris to port your TBW throttle body an he offeres a transition ring to smooth out the difference in diamerters.

Sure you could switch to some LS3 style heads, especially is your changing the intake. Care does need to be taken due to the larger intake valves but your PTV clearance should be ok. You can reuse half of your bushed CHE rockers and I have a set of offset rockers that could be bushed by them.

That route is pretty expensive since you're replacing so many parts. Think the best "bang for the buck" would be a cam, but you will give up a bit of the nice idle. I don't know if I would replace the heads, but I would consider the intake (and save the 90 for your other LS2). If you didn't want to buy a new intake you could port out the FAST 90mm on the car right now. It was worth about 10hp when we tested one on the engine and I know you love tinkering like that.

Keep in mind the engine put out about 570hp and 535 ft-lb (488 rwhp and 475 rwtq as I recall).. which is pretty stout.

[Damn True]

Where is this engine going to live?

[David Pozzi]

8 psi make any head flow better. ;-)
Yes, I've been thinking about that.

[David Pozzi]

Steve,
Thanks for the added info. Do you have flow numbers for those heads with the extra port work?
It just seemed to me that those are the smallest port size they make and made more for an LS1. But it isn't worth buying new heads for an extra 20 hp top end. I don't want the idle to get rougher, or lose low end torque, but was looking at a way to boost top end a little. Maybe porting the intake and Throttle body would be a good idea.
David

[WS6]

I wouldn't touch the engine beyond maybe porting the intake and TB. Those torque numbers are fantastic. You rarely see anyone talking torque numbers and location when building the LSx engine. I have no doubt LS3/L92 heads would make more peak power. I also have no doubt that you'll lose low end torque.

If you want to try a cam change, go wider on LSA. Narrower moves power band up, wider brings it down because it keeps the intake charge in the cylinder longer. You could try the XFI grind possibly. I'm assuming this is a Comp XER cam currently. Check the mid range lift numbers on the XFI cam though. I know overall it is higher but power is made in the low lift area not at .600 lift. However, having just as good a base but even more top end flow could help you.

I'd still not change it though. I say run it. It's great the way it is.

[CarlC]

Yes, I've been thinking about that.

If you are at Willow on March 4 take mine for a ride. Yours would be MUCH faster.

[Steve1968LS2]

Steve,
Thanks for the added info. Do you have flow numbers for those heads with the extra port work?
It just seemed to me that those are the smallest port size they make and made more for an LS1. But it isn't worth buying new heads for an extra 20 hp top end. I don't want the idle to get rougher, or lose low end torque, but was looking at a way to boost top end a little. Maybe porting the intake and Throttle body would be a good idea.
David

They make smaller.. I think they make a 195.

That was forever ago.. I called Tony Mamo today and left a message.. I think he will have that info.

Port the intake.. or buy and port a 102mm and then port the TB. You could go one step bigger on the cam and most likely never notice it.

[Steve1968LS2]

I wouldn't touch the engine beyond maybe porting the intake and TB. Those torque numbers are fantastic. You rarely see anyone talking torque numbers and location when building the LSx engine. I have no doubt LS3/L92 heads would make more peak power. I also have no doubt that you'll lose low end torque.

If you want to try a cam change, go wider on LSA. Narrower moves power band up, wider brings it down because it keeps the intake charge in the cylinder longer. You could try the XFI grind possibly. I'm assuming this is a Comp XER cam currently. Check the mid range lift numbers on the XFI cam though. I know overall it is higher but power is made in the low lift area not at .600 lift. However, having just as good a base but even more top end flow could help you.

I'd still not change it though. I say run it. It's great the way it is.

The current cam is a 238/240 112+3 ... It was the biggest (at that time) in the XER line for off the shelf stuff.

Here's a dynograph, we were having problems with the XFI running the engine on the dyno and I think the peak numbers are a bit low (was breaking up a bit).

Still, the low end torque stuff is good.

Here's the engine dyno (compared to the before engine)
https://static1.pt-content.com/images/pt/2010/02/2edwav6-1.jpg

Here's the chassis dyno (rear wheel compared to with the broken spark plug)
https://static1.pt-content.com/images/pt/2010/02/dnhd10-1.jpg

Here's what I wrote about the AFR heads from back in '06


The LS2 crate engine ships with some pretty good heads that, with port work, can flow some respectable numbers. However, we decided to go with AFR’s newly designed 205cc Mongoose street heads. AFR states that the flow performance is 300 CFM at .600 lift (about 70 CFM over a stock LS1 head) and that the heads feature 2.020 intake and 1.600 exhaust valves with iron ductile interlocking valve seats. The AFR heads weight a bit more than the stockers, but that weight is in the right places with a .75-inch thick head deck, reinforced rocker stud bosses, and thick wall runners.

[WS6]

That's so pretty I'd be afraid it wouldn't like a cam change. Sure on paper a cam change should do better if spec'd correctly but that doesn't mean it will.

Steve, why didn't you have a "custom" cam spec'd when you had the 402 built? Comp lists the lobe numbers online. They did have them in the back of the master catalog for a long time. I used to laugh at all the people selling "custom" cams to customers for a huge mark up. They went through such secrecy to hide the cam info too. All they did was flip to the back of the catalog and order based on lobe numbers and told Comp what LSA they wanted it on. Truly custom would mean they spec'd the lobe design which very few really did.

[Steve1968LS2]

That's so pretty I'd be afraid it wouldn't like a cam change. Sure on paper a cam change should do better if spec'd correctly but that doesn't mean it will.

Steve, why didn't you have a "custom" cam spec'd when you had the 402 built? Comp lists the lobe numbers online. They did have them in the back of the master catalog for a long time. I used to laugh at all the people selling "custom" cams to customers for a huge mark up. They went through such secrecy to hide the cam info too. All they did was flip to the back of the catalog and order based on lobe numbers and told Comp what LSA they wanted it on. Truly custom would mean they spec'd the lobe design which very few really did.

We did have a custom cam in the old LS2.. when it died from an oil failure we had to rush an engine together.. at that time it was almost 2 weeks for a custom grind so we picked the best from thier "off the shelf" offerings. Not sure if the lobes were one-offed but the cam was designed by COMP and worked well, just no time to do it on the new engine.

And it's true that there are very few "truly custom" cams.. most are just a mix of existing lobes.

[WS6]

Understandable. When you have a dead line you have to meet you may have to make compromises. I'd say it worked well for you in the end.

[BonzoHansen]

Where is this engine going to live?

See how he skipped your question? See that? :enguard:

[Steve1968LS2]

See how he skipped your question? See that? :enguard:

Nothing to see here... move along...

[David Pozzi]

I just need to keep it out of Mary's evil grip! I have 2 cars it could go in, or a third I haven't even built yet.
One problem is, I was fairly far along building a Brodix tall deck block 18 deg headed 427 for my 67 and I don't know if I should sell it or finish it and use it in the car.

I like how smooth Steve's engine runs on the street, and the torque is great. It looks like working on the intake and Throttle Body would help. Cam change? Maybe.

Two things about a supercharger, I think the compression is too high, and it would add some extra weight.
David

[79-TA]

Perhaps old fashioned cylinder head shaving is an option? Maybe a comparable but thinner head gasket is now available? Or are the valve clearances already too tight for that?


You could get really fancy and start looking into variable cam timing. Cam phasers are becoming more common on the new GM engines. Sadly, I have no idea if it is remotely practicaly to retrofit such a setup onto an LS2.

[John Wright]

I have 2 cars it could go in
one being a red 73 camaro?<fingers crossed for Mary>:smoke:

[WS6]

I just need to keep it out of Mary's evil grip! I have 2 cars it could go in, or a third I haven't even built yet.
One problem is, I was fairly far along building a Brodix tall deck block 18 deg headed 427 for my 67 and I don't know if I should sell it or finish it and use it in the car.

I like how smooth Steve's engine runs on the street, and the torque is great. It looks like working on the intake and Throttle Body would help. Cam change? Maybe.

Two things about a supercharger, I think the compression is too high, and it would add some extra weight.
David

I wouldn't put an SC on the engine.

Something to keep in mind if you aren't already aware. The FAST 102 has different runners available for it. You can test and tune the intake essentially. It's not a cheap setup but I think I would lean this direction so you can hopefully optimize the power with a day worth of dyno tunning. VMax Motorsports offers a cable operated 100 or 105mm billet throttle body that is gorgeous and will fit the front of that intake. I'm betting you'll want a 95 or 100 and not the 105 for great throttle response. Check with Pete at VMax or Mike Norris as he carriers VMax parts as well.

Going with a carb style intake may be possible also. I can't remember but I believe they are all single plane only which could hurt bottom end if the runners are too large. It will definitely help top end though. I think the FAST 102 would be better simply because you can change runners.

Then again, loose just a tad on the bottom but gain a bunch up top may work better on the courses you'll run. See how this could get out of hand quickly, lol.

[David Pozzi]

On the One Lap Camaro I have to watch out to not open the throttle too wide or the engine lays down a little at low speeds. Penny didn't do that at all but perhaps throttle by wire has something to do with it.

The FAST 102 might be a good way to go. Does it fit the AFR ports? It's $400+ to port my current manifold, so maybe I could put that money towards a new intake. and a 95mm TB. Does the FAST 102 benefit from any porting work?

[Damn True]

See how he skipped your question? See that? :enguard:

A conspicuous omission to be sure.

I know what options are available.

Build it David. Build it.

[Steve1968LS2]

On the One Lap Camaro I have to watch out to not open the throttle too wide or the engine lays down a little at low speeds. Penny didn't do that at all but perhaps throttle by wire has something to do with it.

The FAST 102 might be a good way to go. Does it fit the AFR ports? It's $400+ to port my current manifold, so maybe I could put that money towards a new intake. and a 95mm TB. Does the FAST 102 benefit from any porting work?

Yea, the now 102mm will work fine.. I can get you a discount on the intake and the rest is just plug and play.

You can port your own intake.. especially with your skills. Not "hard" just time consuming.

All intakes benefit.. but my guess is that the 102 will be good out of the box considering the heads on the engine.

Mike Norris is the guy to talk to about massaging your TB.

[Gandalf]

Call Charlie at RPM Motors. He's a well respected LSx engine builder and tuner, esp in the Corvette community.

G.

[JMarsa]

I can't see any potential work being worth the time or $$.

That's a 8K motor to recreate and you're practically at 500 RWHP. I've studied the dyno section of ls1tech for years and it takes a lot of money to get 500 RWHP on gen III technology. The new LS3s are cheaper to get there.

Cam swap $500 in parts.
Head milling + $75 gaskets and new head bolts
Intake - $500+
TB Port - $125 for 10HP?

Read any of Tony Mamo's posts...these are the details that get you the magic number but the investment is too much in my opinion. A new tune would probably move the power around for effectively than new parts.

--JMarsa

[David Pozzi]

JMarsa,
New tune?
Are you saying I can have the ECM tuned and get more power? It's already been dyno tuned.
A new cam costs $500? Why?
I won't mill the heads, not worth it.
TBI port, that's a lot for 10hp, but it looks cheaper than the other choices.

The intake and TB has the most potential for the money. I'd have the old one to sell to offset buying a new one. I can port match or smooth up a new intake myself, just haven't done an LS intake before.

If the TB got me 10hp and intake got me 20, that's 30 hp, that would put me right at 600hp. If that could be done with next to no loss of low end it is sounding good. A little more cam and who knows?

I may not decide to do it, but I need to hear my options now, while the engine is still out of the car. I have more reading up to do on these engines.

I didn't want to confuse things by bringing this up, but I also have another engine that could use the old FAST 90 intake and AFR heads, and I could buy new parts for the 402, like new intake and ported LS3 type heads.

[JMarsa]

Usually a dyno tune will get you top numbers. But you can have a tuner spend a day with the can on the street (forgot you don't have the engine installed yet) and he can tweak the timing and fuel to slide around the power curve a bit.

Selling parts like an intake to offset the cost of new ones will bring you about .75 on the dollar. It's not like they wear out and there's strong demand.

Usually a cam kit is purchased, cam, lifters and pushrods (maybe you won't need new ones) here's some examples:

http://www.thunderracing.com/catalog/?action=vshop&vid=7&pcid=51


Instead of an intake I would go with a UD pulley and possibly a EWP. As said earlier, it doesn't look like your air limited. Good headers can made a difference, but it depends on the car, on a 'vette you can see a 10-15HP variance between the vendors.

On ls1tech this guy is local to me: 'allngn_c5 (http://www.ls1tech.com/forums/member.php?u=61774)' he's spent a ton of dough going from 490 RWHP to:

LS2 402 - 541 rwhp 505 rwtq Tuned by Vengeance Racing
TFS 215's (59cc) Custom Cam, 1 7/8 ARH, Ported FAST 92, UD Pully, EWP

--JMarsa

[WS6]

If your current FAST 90 isn't ported, get that done. I missed that and thought you had the LS2 intake on the engine. The differences between your engine and the vengeance 402 aren't worth the efforts. They got nice peak numbers out of the car but the torque isn't much broader than your curve. It's moved up in the RPM band a tad but holds on longer. Better intake will be the cheapest way to extend your torque band into the upper RPMs which is the biggest advantage that engine has over your current setup.

[David Pozzi]

Sorry I don't fully speak LS yet. What is "possibly a EWP" ?
Thanks for the info guys!
David

[JMarsa]

:-) electric water pump, Under drive pulley = UD

--JMarsa

[madmax]

Another thing that would help would be trading out the FAST 90mm intake for thier brand new 102mm cathedral port intake.

I've been hearing that the jury is still out on the 102 and may not make that much of a difference over the 92, especially on a motor like this (may be different on ultra-high hp motors). From what I hear little to no portwork is possible on that manifold.

Like WS6 said, if the 90 isn't ported, do it. I know that Jeremy Formato (great tuner down here in FL) is getting around 18rwhp/tq across the entire band from ported 92s (not sure about the 90). He's currently running a special on both TBs and manifolds for like $375 or $400 and does excellent work.

An electric WP would definately free up some horespower but are also a little pricey, but at this stage there isn't much left to do. The port would get you damn close to 500whp, and the pump over it.

This is from what very little I know lurking on various LSx sites.

Max

[David Pozzi]

Thanks Max. I'm lurking a lot too! :)

[madmax]

http://www.ls1tech.com/forums/12670469-post20.html

There are a couple LSXR numbers. Looks like it is good for about 12-15hp over a stock LS3, with no portwork possible (hardly impressive)

Dyno:
http://www.ls1tech.com/forums/12356431-post22.html

So... you can make those kinds of gains by porting a stock intake, and even more with ported FAST 92 (again, I don't have any info regarding the 90).

Here is a link to the Formato specials: looks like a FAST + TB is $375. I was wrong about the numbers; he is getting 15-17/18-21 on a stock LS2 manifold. Not bad.


http://forums.corvetteforum.com/c6-z06-discussion/2522523-ported-intake-throttle-body-and-tuning-special.html

[madmax]

David -

Been reading a lot of good things about the 102, especially on LS2s. I'll try and dig up some links, but the general consensus seems to be that it flows like a champ and would be great for your application. I know this is contrary to some of the early reports I posted... just trying to get you some good info.

Max