Considering L35 swap

[Couger1968]

I started to rebuild my engine and found a set of L35 heads for $80. I do not know the condition. They are on a 1994 s10. I am considering having them done and using them. I have eagle rods and arp studs. I haven't decided on the pistons. I already bought a crane184211 - CompuCam ,but I don't know if it will be big enough, maybe with1.6 rockers?.
- Lift (I/E) - .407/.429
- Duration @ .050 (I/E) - 194/204
- Lobe Separation - 112 deg
I have done some mods already, msd 6a,walbro fuel pump and reg,Aux intercooler with fans and tranny cooler. I am running a ultimate chip. I think I will need a Moates Ostrich Emulator. I think I would also need a 20g turbo and a 2400-2800 stall converter, #50 injectors,but I am way over budget already. So what I would l like to know is what else am I going to need, and any suggestions for parts(turbo,converters,pistons,injectors). I want it to look stock under the hood. And if I don't buy the heads. I was planning on just putting in that cam with a 2400 converter and running the ultimate. I was looking at Sealed Power ZWL2441F30 Speed-Pro Forged Pistons as possible upgrades for my pistons. Thanks

 

[wildphil]

Re: Considering L35 swap

L35 heads work well. They would be a good upgrade.

 

[Couger1968]

Re: Considering L35 swap

Can I bolt them on with my current setup(chip, turbo,and new cam) and get it running again, then buy upgrades. I figure I will need the emulator first.

 

[sytyguy]

Re: Considering L35 swap

L35s are a transparent mod. They will require nothing additional to work, not even tuning. The tune can benefit from being altered to accommodate the L35s, but it's not required. The flow increase is enough to help performance, but not enough to cause tune/compatibility complications.

 

[Couger1968]

Re: Considering L35 swap

What I don't understand is if I can make 22psi with my factory turbo, why would a person need a bigger turbo to make 17-19 even with l35 heads, it must be because the cam lets so much more air in that a 17g will not keep up. It looks to me that unless you run race gas or alky injection you can't safely run over 19 anyway. I should say that I have only raced it a few times, years ago, and was trying to run 20psi. Is that why I never could get over 13.8. It would pull strong for 1/2 the track then just kind of lay down for the rest,and my knock always looked ok. I don't remember losing pressure, if it was only a psi or two. Another thing I don't really understand is running a TC lockup switch. Does it try to lock it up right away while you are launching, if so why would you want a high stall converter in the first place. I am ignorant when it comes to these type of things.

 

[AUSyTyIN]

Re: Considering L35 swap

The pressure is created by resistance. The better a head can flow, the lower the pressure to move the same amount of air (cfm). 22 psi would be the same HP on stock heads as 17 (or so, don't quote me on this) with L35s. CFM is all you really care about (well, besides temp). The psi is just there to increase the CFM. Make sense?

The lockup switch is for once you are rolling. The high stall converter is to get the engine into an rpm where it's moving enough air out the exhaust to spin the turbo fast enough to create enough pressure. So yes, using a lockup switch on a launch would be a bad thing.

 

[Couger1968]

Re: Considering L35 swap

That makes sense, so a person should mount the switch with a button you could hold down after your off. Will my stock turbo have enough to run 17-19psi

 

[sytyguy]

Re: Considering L35 swap

What I don't understand is if I can make 22psi with my factory turbo, why would a person need a bigger turbo to make 17-19 even with l35 heads, it must be because the cam lets so much more air in that a 17g will not keep up. It looks to me that unless you run race gas or alky injection you can't safely run over 19 anyway. I should say that I have only raced it a few times, years ago, and was trying to run 20psi. Is that why I never could get over 13.8. It would pull strong for 1/2 the track then just kind of lay down for the rest,and my knock always looked ok. I don't remember losing pressure, if it was only a psi or two. Another thing I don't really understand is running a TC lockup switch. Does it try to lock it up right away while you are launching, if so why would you want a high stall converter in the first place. I am ignorant when it comes to these type of things.

Not to be mean, but that is the single most misinformed paragraph I've read in a while.

There is no need to run a larger turbo to achieve 20+ psi with L35 heads. If a person is having that issue, then there is another unresolved problem with the truck. Turbos are simple devices....and they will continue increasing their rpms until they self destruct, run out of driving force (turbo too large, engine too small, etc....), or an external force interacts (wastegate, etc...).

Now, running higher boost levels will require several things.

1) A 3 bar MAP sensor - perhaps it's not required, but running over 15 psi w/o one is like driving with your eyes closed. You cannot react to what you can't see. Same thing with the MAP sensor. The stock 2 bar will only read up to ~ 15 psi and anything over that it can't see....so it can't tell the ECM.....so the ECM can't fuel for it.

2) A chip setup for higher boost operation. The factory chip is a 2 bar (see above) chip and won't work properly with a 3 bar MAP sensor. Now, let's say you do have a 3 bar MAP and chip, but the overboost limit is 18 psi....well, if you run over that, you'll hit the overboost fuel cut. Gotta have that set with your max boost in mind.

3) An aftermarket boost gauge. If the ECM can see it but you can't, you're left guessing at how much boost you run.

4) Enough fuel. For the stock turbo, a healthy pump and FPR can keep up with 18, 20, 22 psi no problem. Walbros and AFPRs only help.

Now, having said that, you may begin to wonder why anyone would upgrade the turbo on a stockish truck. Well, the stock turbo's peak efficiency is often well below what some people demand of max boost. For instance, if you run 24 psi with the stock turbo, you are operating it at 5-6 psi above it's peak efficiency and as a result, it will begin to become more and more inefficient as you go up. What does that do? It generates more heat, giving your IC system more to overcome.....and there will be a saturation point. The stock turbo is a perfect example of diminishing returns. You get higher boost with it, but you're increasing the IATs significantly as well, offsetting the boost gains.

So, what do you do? Well, some choose to run a more efficient turbo. Others put water/meth injection on. Others beef up the IC system. Some do all 3. There is no right/wrong answer as the stock turbo has been proven to be high-11 second capable (though, those are rare examples). Really, it's your call.... but the experience you seem to have had, is not a result of the turbo (unless it's damaged - and this is common so check your impeller blades). Most likely it was an external factor affecting your overall performance.

 

[sytyguy]

Re: Considering L35 swap

22 psi would be the same HP on stock heads as 17 (or so, don't quote me on this) with L35s.

It's closer than that. Mark (old GAST member) did dyno pulls with a stock truck and then 2 days later after an L35 swap.....same stock turbo/IC/etc.... He only saw about a 20 HP increase at 4200 rpm with the same boost (Ultimate set on T2-22). These were unmodified L35s, but seeing the results, that puts the boost gap closer 2 psi, not 5 psi.

 

[sytyguy]

Re: Considering L35 swap

I know I have bad or lacking information. No one does this sort of thing around my area and that is why I am reading this board. I just want to make the right decisions so I don't go backwards. I am a dummy

Not at all calling you a dummy. We all started somewhere. The main thing is that we've got over 2 decades of info on this board, and most of what is asked is info that has been covered before. It never hurts to ask a question, but do your best to educate yourself beforehand. Beyond that, we are all here to help. :tup:

 

[Couger1968]

Re: Considering L35 swap

I am sorry if I repost questions. I do look up articles on here and find lots of information, it is great source. The problem I have here is overload and sorting out information. These trucks are complicated and with many variables, so I try to give specific information and ask dumb questions to try to make informed decisions. I like to get a different perspectives on things in case I am misdirected. I am just trying to avoid costly mistakes.I do appreciate all the advise and I do apologize.

 

[dgoodhue]

Re: Considering L35 swap

You can always add the turbo/injectors/torque converter later as your budget allows. Using a different cam will ideally require a custom tune. You may want to do the L35 heads along with the injectors so you will have the tune close when you decide to upgrade the turbo and stall converter.

 

[AUSyTyIN]

Re: Considering L35 swap

It's closer than that. Mark (old GAST member) did dyno pulls with a stock truck and then 2 days later after an L35 swap.....same stock turbo/IC/etc.... He only saw about a 20 HP increase at 4200 rpm with the same boost (Ultimate set on T2-22). These were unmodified L35s, but seeing the results, that puts the boost gap closer 2 psi, not 5 psi.

Yeah, that was just a WAG to use for an example.

 

[Couger1968]

Re: Considering L35 swap

My bearings were bad,and all I was looking for in the beginning was something just over stock. I wish I had knew that the L35 was as easy as they say that would have probably have been enough for me. The problem now is that I am in too deep, parts have been bought. I have a custom cam already and I am not going to tear it apart again. So I think from what i understand ,I can use the turbo I have as long as I don't expect a lot out of it(15-17). My converter is getting bad so I am going to replace it. I still don't know with what. My ultimate chip will work for now and down the line I can buy an emulator to tweak everything. I really don't need a race truck and don't care if I have every pony out of it.

 

[Couger1968]

Re: Considering L35 swap

I went to look at the heads on the 94 they were the same casting number as my stock head, it is confusing since it has vortec written all over it and has cfi.The intake had aftermarket gaskets so maybe they were swapped at some point. I found a 95 with casting numbers 14099064 which looks like a L35 number. The problem is the truck had 175000 miles on it and they want $80 for the heads. Are they worth it, they probably would need a rebuild. Should I try to find 10238181 or 10240209 heads instead.

 

[MoJo]

Re: Considering L35 swap

Ten months ago, I bought a pair of 1993 L35 CPI, VIN "W" heads on e-bay for $150 plus shipping. They are casting number 14099064 with a 9-29-1992 casting date. Those are similar to the 10228181 heads with the main difference is that some of the "064" heads do not have screw in rocker studs so you need to check that before buying them. Factory screw in studs will save you about $100 when you rebuild the heads.. All "181" heads have screw in rocker studs and the valve throat angles are different from the "064" heads.. All the L35 CPI heads have "eyebrows" at the top of the intake ports for the injector valves. The "eyebrows" do not present a problem when using thee L35 CPI heads with TBI or turbocharger intake manifolds if you use L35 CPI intake manifold gaskets. You should plan on rebuilding any 1992-1995 L35 heads with new valve springs and new valves. I would be reluctant to buy any heads that have already been "reconditioned" by someone that you don't know. Have them checked for cracks and rebuilt by your favorite machinist. I had my L35 "064" heads rebuilt using Ferrea 5000 series small block Chevy valves, Comp Cams 26918-12 beehive valve springs with 10 degree retainers and + .050" locks. Set the valve springs at 1.750" instead of the standard 1.700" in order to reduce the seat pressure from 163 lb. to 144 lb. and 330 lb. open pressure at .500" valve lift. I used Comp Cams 875-12 reduced travel roller lifters with that much spring pressure.

Disregard the "Vortec" moniker. That was a Chevrolet marketing trademark that was introduced in 1988 on the TBI swirl port heads that used "vortex technology". Chevrolet thought it was a "tricky" name so they started using it on a wide range of engines.

 

[Couger1968]

Re: Considering L35 swap

These had screw in studs. My machinist thought that a good rebuild would cost around $600. I see that you still can buy 181 heads on ebay for $300 that are rebuilt. Do you think if they were magnifluxed with new springs and valves they would be ok,it doesn't say if they were. What about valve guides? Don't they put bronze ones in or something. My machinist said them and if the seats need to be changed is where the cost would be.What bothers me is that the ones on ebay say if you disassemble to inspect them it voids the warranty.

 

[wildphil]

Re: Considering L35 swap

Having a set of heads rebuilt is a little costly. I am sure the price varies some depending on the area of the country you live in.

I picked up a set of L35 heads at a salvage yard for $60 I think. I bought a set of ferrea 2;02 1:60 valves on sale for $100, ARP screw in studs for around $60, valve springs under $100.

At the machine shop labor is not cheap. The heads were checked for cracks. All the valve guides were replaced. The heads had to be cut for the larger valves. And assembly of the heads. The machine shop cost was about $450. So it cost me just under $800.

If the valve guides are good and the heads use stock size valves. The price would be hundreds of $$ less.

 

[WyoSyclone]

Re: Considering L35 swap

Having a set of heads rebuilt is a little costly. I am sure the price varies some depending on the area of the country you live in.

I picked up a set of L35 heads at a salvage yard for $60 I think. I bought a set of ferrea 2;02 1:60 valves on sale for $100, ARP screw in studs for around $60, valve springs under $100.

At the machine shop labor is not cheap. The heads were checked for cracks. All the valve guides were replaced. The heads had to be cut for the larger valves. And assembly of the heads. The machine shop cost was about $450. So it cost me just under $800.

If the valve guides are good and the heads use stock size valves. The price would be hundreds of $$ less.

My L35's should be done in the next week or so. I'm anxious to see where the price comes in on them.

For those looking for L35's, here's a link to a spreadsheet I've been working on for a few years now trying to document all the differences in LB4/L35/Vortec casting #'s.

http://r.b5z.net/i/u/10053520/f/4.3_Cylinder_head_application_guide.pdf

and where I host it on my website...

http://zddppluscentral.com/faq

 

[jklein68]

Re: Considering L35 swap

I went to look at the heads on the 94 they were the same casting number as my stock head, it is confusing since it has vortec written all over it and has cfi.The intake had aftermarket gaskets so maybe they were swapped at some point. I found a 95 with casting numbers 14099064 which looks like a L35 number. The problem is the truck had 175000 miles on it and they want $80 for the heads. Are they worth it, they probably would need a rebuild. Should I try to find 10238181 or 10240209 heads instead.

Lots of good info here. I'm in Madison, PM me some time.

http://www.syty.net/forums/showthread.php?t=79338&highlight=head+casting+numbers

http://www.syty.net/forums/showthread.php?t=8722&highlight=l35+casting+numbers