What would my fellow GA16DE owners want from a built head? Massive HP/TQ gains in just the top-end or the best possible Mid-Top end power (something that's streetable and would still have some bottom end power)? I'm just curious because I have an automatic transmission and even if I upgrade to the JWT ECU, the car still won't change the shift points. The highest rpm it will shift at without manually shifting is 6,200 rpm. I'm also going to be using a 3,200 rpm stall converter from Level 10 , so my basic powerband would be something like the following at full throttle:
1st gear - 3,200-5,600rpm
2nd gear - 3,900-6,200rpm
3rd gear - 4,000-6,200rpm
4th gear - 4,200-redline
If I get the combustion chambers welded and reshaped to get a higher compression to 10.5:1 - 10.8:1 will I be required to get an ECU upgrade? Could the car be run on 92 or 93 octane and be safe without the ECU upgrade till later? Also, if the head was built to the JWT cam specifications would it be safe to run stock cams until later on? About how much can the cams help with higher compression, headwork & motorwork, and all the bolt-ons (I read something like 42 more hp over stock at 7300rpm on sentra.net but that's without headwork & motor work, right?)? I'd like do these things in stages rather than spending money on the DPR headwork, JWT cams, and the JWT ECU upgrade all at once.
This is what I would like to end up with if everything works right: DPR Stage VI GA16DE Head (mild pocket porting w/ all DPR's goodies) DPR Ported Intake Manifold matched w/
SE-R 60mm Throttle Body JWT Cams JWT ECU w/ VTC enabled
If VTC was not enabled by JWT in the ECU upgrade, how much power will be lost or would it be noticeably different? Sorry for all the questions, I'm just really curious about the options. DPR needs all the info that I can give them to make this all work properly. I'm hoping that I don't have to end up replacing it after a year of street use. I just want the engine run safely, dependably, cool, and powerful for a long time.
For the reliablilty/dependability/safety, should the bottom end be worked on at the same time as the head? What should be done to it? I've read that ARP rod bolts are needed. Would a metal head gasket be needed or is that just an extra precaution? Is there anything else? What has to be done to keep it cooled properly? Would boring it out help that much or would it be a waste of money if the head can be welded and reshaped for higher compression? Like everyone else, I'm also on a budget. So far the prices I've found are close to: $1100 DPR headwork w/ intake manifold ported ($1000 for headwork then $100 for intake manifold), $595 JWT Cams, $595 JWT ECU Upgrade, $269 VTC addition to JWT ECU.
Thanks for your time,
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
I don't know if you will need a copper head gasket, I've haven't heard much of any good news about them, my machinist said that he runs a 17.1 compression (on his turbo drag car that runs high 7's) with a felpro head gasket. The felpro gasket he showed me had a copper band around each cylinder and the rest was just gasket material.
I've been kinda reading about your car troubles on the mailing list so I've been following along with your car. Your engines a rebuild right? The headwork and all that other info I'm sure someone else can help you with or you can find the info on Sentra.net...
I was thinking about what you said about boring out the cylinders and ARP studs.... my point is that you have a rebuilt engine and if you want to strengthen the bottom end you're basically going to be rebuilding it again...
One more thing, if you manual shift your auto you should be able to hit 6900 too! If you have the ecu upgrade it'll help in that area also.
I have an ATK remanufactured engine in my car with an Aamco rebuilt transmission. I'm looking for another head to get the headwork done on and then I may bolt the head onto my current block. Would the new remanufactured block be good enough? Anyone know if these ATK's are blueprinted or balanced before sending them off? The other option is to find another block & head and then send them off to get worked on with all the modifications and then just swap it in. That way I can keep the ATK for the warranty (5yr, 100,000 mile) as a backup motor and I can keep my transmission working.
I'm not interested in swapping to a 2.0 because of all the things necessary to do the swap just for 140hp. Plus, I already have all the bolt-ons for the 1.6L (Custom CAI, NGK wires & Plugs, Nology Wire amplifier, Pacesetter Header, Custom 2" Mandrel Exhaust w/ RT Hi-flow Cat/Dynomax Ultraflow muffler/Thrush Glasspack as resonator, and a 3,200rpm stall converter). So, it would be a waste of my money to swap where I can optimize the products that I currently have.
Regarding the manually shifting, I've tried to manually shift the auto but it seems to redline at 6,300 or 6,500rpm.
Anyways, I'd still like to know more information to make this build a successful one and I think DPR might be willing to work a deal for all of us. They just want as much info as we can give them to make it easier to make the work possible and well within our budgets.
I keep reading over and over again the information on sentra.net and I haven't found anything about raising the compression in the head by welding and reshaping the combustion chamber, oversized valves, or lightened valve springs. I even looked at mathermotorsports.com and I didn't see them saying anything about the ecu needing to be modified but I could be wrong. Please someone give more information on what to look out for and what should be done. I'm really wanting to learn more.
Oh yea, one more thing. With getting higher compression pistons, what advantages are there from keeping stock ones and coating everything w/ the Stage VI head with raised compression vs. the 11:1 CR pistons? Is it safer to run higher compression in just the head vs. 11:1 CR pistons? Is it a better bang for the buck to do the stuff w/ the head? Anyone know how much the Swain tech coatings or other special coatings to all the parts of a stock bottom end and then on a Stage VI head?
Thank's for your time,
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
Originally posted by Joshb13sentra I don't know if you will need a copper head gasket, I've haven't heard much of any good news about them, my machinist said that he runs a 17.1 compression (on his turbo drag car that runs high 7's) with a felpro head gasket. The felpro gasket he showed me had a copper band around each cylinder and the rest was just gasket material.
Is he running acetone?? That's really high compression! Do you think you can ask him if an aftermarket head gasket would actually help or be necessary on a moderately modified motor like the GA16DE? I would appreciate it.
Anyways, what do you think the stock GA16DE cooling system would be able to handle from raised compression in the head? How much do you think coatings would help reduce temp? How long should they last in a street motor? I just don't want to spend a lot of money on something that will just wear away after 10,000 miles.
Thanks for your time,
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
I had mild head work done. Port and polish, 3 angle valve job, valve bowls swirl polished, swain coatings, etc... Anyway the BEST way to raise compression is with pistons. There is not a lot of room to work with on the cylinder head, so welding and reshaping seems like it would be a waste in comparison to the pistons. If I wanted a high compression motor I would def. contact Mike from Motivational and get a set of those pistons. Go with some custom connecting rods, and go from there. As far as valve train modifications, no one has really messed with springs and retainers yet. Mainyl because the GA16 has not been pushed to those limits yet (emphasis on the word yet). Be careful with valve springs because you can do more harm than good if you don't match them to the rest of the valve train properly. Oversized valves have also not been performaed to my knowledge. I will be testing my cylinder head within th next month, with as small as the ports on the GA16 are, I suspect it will respond well to the head work and JWT cams.
Is it safe just to do head w/ intake manifold and throttle body first before ECU mods and cams and pistons? or how would you go through this in stages?
Stage 1 - DPR Headwork w/ Throttle body & intake manifold and put on current block
Stage 2 - Purchase parts for bottom end (rods, pistons, etc)
Stage 3 - Send block to DPR for bottom end work w/ rods, pistons, etc. (should displacement be changed?)
Stage 4 - Purchase JWT Cams & JWT ECU w/ programming for VTC, Cams, 10.5:1 or 11:1 pistons
Stage 5 - Install DPR'd block, Install JWT Cams, Install JWT ECU
Would 11:1 pistons be streetable? Would anything have to be done to ensure cooling of the block? Would the oil supply be enough for the block? Aren't the GA16DE injectors enough for NA?
Wes, I'd like to know how it goes with the testing. Please keep me informed.
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
I made a mistake on the prices for the DPR headwork. Here they are:
Stage IV $850
Stage VI $1200 W/ Manifold
Stage VI $1500 Full welding and combustion chamber modifications
Stage VI $2300 - added valves and coating etc
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
I made a mistake on the prices for the DPR headwork. Here they are:
Stage IV $850
Stage VI $1200 W/ Manifold
Stage VI $1500 Full welding and combustion chamber modifications
Stage VI $2300 - added valves and coating etc
seems kinda pricy there.. your price for the stage iv, is that if you bring your car to them..? or for you to send your head out?
seems kinda pricy there.. your price for the stage iv, is that if you bring your car to them..? or for you to send your head out?
That's the price for your head shipped/brought to them (DPR in california). I think the prices are pretty good compared to the places around here (DFW). One of the shops over here was gonna charge something like $400 just to port the intake manifold (DPR charges $200). And for the headwork, they quoted something like $2000-3500 plus, they don't even test the flow and stuff. Another reason why DPR is a little more expensive is the quality of work that is done. Sentra.net recommends DPR for headwork and JWT. JWT isn't offering headwork for the 1.6 right now (atleast that's what they told me). Here's what DPR offers for each of their stages (not specific to the 1.6 head, some things are done differently depending on application: turbo, NA, NOS, etc.) Also, I think he offers 5 angle valve jobs at no extra charge.
Stage V
Stage IV plus...
Cylinder Head Deburred & Blueprinted
Combustion Chambers C.C.'d
Detailed Matched Intake Manifold Fully Ported to Head
and Throttle Body
Match Port Exhaust Manifolds
Port Faces Lapped Flat (Studs removed and reinstalled)
Decks Milled & Lapped (At any amount with no additional charge)
Radiused Cut Seats
Stage VI
Stage V plus...
Combustion Chambers Welded & Reshaped, (clover-leaf pent-roof design)
Intake Valves Lightened
Includes Valve Spring Shims as Needed
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
I was thinking that your original prices were a bit low. I was originally oging to have JWT do the headwrok on my 1.6. After some research I found a local shop that had the resources to do the work properly and the knowledge to not seriously mess it up. I think I paid about $600 for the work (port and polish intake and exhaust ports, multi angle valve job, polished bowls etc...) and another $300+ on the Swain coatings. I recently dropped off the head and JWT cams so that they could assemble everything and check the clearance and adjust the shims if necessary. Heck that was included in the price so why not let them do it. I realize that the cylinder head is not the same as a DPR head, but I am very impressed with their work thus far, and as lousy as the stock head is I'm SURE we will see some decent gains. Once I get the parts back from the shop I should have everything I need to install them.
Originally posted by wes I had mild head work done. Port and polish, 3 angle valve job, valve bowls swirl polished, swain coatings, etc... Anyway the BEST way to raise compression is with pistons. There is not a lot of room to work with on the cylinder head, so welding and reshaping seems like it would be a waste in comparison to the pistons. If I wanted a high compression motor I would def. contact Mike from Motivational and get a set of those pistons. Go with some custom connecting rods, and go from there. As far as valve train modifications, no one has really messed with springs and retainers yet. Mainyl because the GA16 has not been pushed to those limits yet (emphasis on the word yet). Be careful with valve springs because you can do more harm than good if you don't match them to the rest of the valve train properly. Oversized valves have also not been performaed to my knowledge. I will be testing my cylinder head within th next month, with as small as the ports on the GA16 are, I suspect it will respond well to the head work and JWT cams.
Do you think the stock bottom end would do fine stock for a while with a modified head w/ cams & ecu?
How hard is it to change pistons and connecting rods in the future, maybe a year after the head? Would you change the displacement at all?
Would swain tech coatings be a better investment than high compression pistons and connecting rods for reliablity? How much of a power difference do you think there is between the two? I think I remember seeing on sentra.net that with 11:1 High compression pistons will only add 5-8 hp, is this true?
__________________
Dan
1992 Nissan SE-R
2001 MR2 Spyder
Is he running acetone?? That's really high compression! Do you think you can ask him if an aftermarket head gasket would actually help or be necessary on a moderately modified motor like the GA16DE? I would appreciate it.
He runs racing gas, It is a high compression but he also tears the engine apart pretty often. When I asked him about a copper head gasket he said he has always had trouble with them. He told me they leak, pain to deal with the sealant supplied, and they cost more than what he spends on felpro gaskets. He said that a good head gasket should be able to hold a higher compression on a 1.6
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