By Costa Gialamas
If you have been following our adventures with Dai Yoshihara in the Middle East, then you have probably read the story of how we converted his mildly built time attack car into a Formula D drift car in just a few days, sending it to Abu Dhabi to compete in a Formula D expansion event. You can read about our adventures from building the car to where we last left off here.
As we left our crew, in Abu Dhabi our VQ35DE Rev Up was dead with a blown head gasket. Unfortunately it was announced that we had another Formula D event in Qatar in 3 weeks. We had gone to Abu Dhabi with our fingers crossed. In the rush to complete the car, we had discovered on shipping day that our car suffered from boost creep and we could not lower the boost to less than 21 psi. The car had to get loaded on a container to Abu Dhabi and nothing could be done about it. At 21 psi our stock engine was pumping out 610 whp.
The car was already dead when we took these shots for the PR people. It sucked pushing it around.
We knew that this was way too much for the stock engine to handle but we had no time to do anything about it. We had flown to Abu Dhabi with ported O2 sensor housings and our plan was to install them on the car to reduce boost to a more livable 15 psi which was the planned native wastegate pressure. Unfortunately, we had packed our B set of tools. Not wanting to be without our good tools for a couple of months, we packed all Craftsman tools with the car. What we discovered was that Snap On wrenches and sockets are much thinner than Craftsman .
Nick Hunter of 5523 Motorsports is an engine builder that JWT uses. Nick is intimately familiar with VQ engines so we figured he could assemble things faster than we could. To meet our timing, Nick built our engine at his house after his normal working hours. Without Nick’s help, we probably could not have met our time schedule.
What this meant was that we could not remove our O2 sensor housings with the thicker craftsman wrenches as there was not enough clearance. We also found that all of the other teams had packed away tool kits with cheaper, crappy tools and believe it or not, no one had tools that would work as everyone had left their pro tools at home and had come stocked with Husky, Craftsman and Harbor Freight stuff.
Our VQ used the older water flow path where coolant enters one end of the head from the block and flows end to end as pictured on the left. This is good for emissions but bad for cooling and the coolant progressively picks up heat as it flows through the head leaving the rearward cylinders hot and bothered. We changed our water flow patten to mimic the new HR and VHR as on the right.
We tried grinding on tools we had to no avail and after 1.5 frustrating days, we had to call it quits and risk running the car as is. Although we had problems with the engine running too hot, everything went fine until the last practice before qualifying when the poor overstressed motor blew its head gasket and we were done. The stock engine had run at over 600 hp for a drift demo, a drag racing demo and three grueling Formula D practice sessions before packing it in. On the street it would have lasted a long time, the VQ engine is strong!
We switched our water flow to mimic the VQ HR model as pictured below. This flow pattern has each cylinder being fed from the block individually as pictured at the bottom. This keeps each cylinder cooler. To run this flow pattern you have to run an HR head gasket and grind the block’s water passage near the bore as shown in this picture in the bottom left corner.
At home after a long and tiring flight, we had to come up with a game plan. Changing head gaskets in the field was going to be difficult and there was no knowing the condition of the engine besides the head gasket. For all we knew the engine could have been warped, damaged by the water or a valve burned or a ring land cracked. It would also be more of the same performance level as well. Clark Stepper of JWT had warned us to keep the revs down and our rev limter was set at 7000 rpm. This gave us a narrow powerband and Dai was having to shift a lot as well as always bounding off the rev limiter which was making the car harder to drive. Worrying about blowing up the engine was also giving Dai stress, he was not driving very well because he was trying not to hammer the engine too hard and was trying to keep it off the rev limiter.
This is the area that must be enlarged on the older blocks.
So we decided that the best thing to do was to build another engine. We would assemble a properly built long block and air ship it to Qatar, Costa would fly to Qatar a week early and install the engine in time for the event. When figuring shipping, customs and other logistics, this would only give us three days to get the parts and assemble the engine.
Our goals were simple; one, the engine had to be strong enough to easily live under competition conditions with no problem. Two, the engine had to have a useable powerband all the way out to 8000 rpm. Three, the engine had to run cooler. We had days to do this.
We used OEM HR head bolts as they are much stronger and are tightened to a higher torque load for better clamping. JWT provided us with this cool chart explaining the difference between VQ bolts.
Jim Wolf Technology was kind enough to give us a spare VQ35DE Rev Up long block they had lying around. The engine went to Nick Hunter of 5523 Motorsports an engine builder that JWT uses. With speed being of the essence, we figured that having someone intimately familiar with the VQ engine would get the job done faster than us. Nick disassembled and prepped the block and heads while we rounded up the parts. The block’s bores and valve job were in excellent shape so we would keep the engine at standard bore with a clean up honing and the heads only needed a slight touch up.
Cosworth HR head gaskets were our gasket of choice. Cosworth gaskets have a folded stopper layer around the cylinder for superior sealing.
Earlier VQ engines had the cooling flow of water in the engine coming up from the block towards the front of the engine, flowing across the head from the front and out of the head to the block at the rear of the heads. This was done so that the heads could be kept warmer for emissions reasons. Unfortunately the coolant is cool in front of the head but gets progressively hotter as it travels rearward leaving the rear cylinders to get much too hot. This leads to flash boiling in the head and overheating.
In development, Cosworth uses this special pressure film to find out how clamping force is distributed. You can see here that the stock Nissan gasket leaves a lot to be desired. Look at the thin red areas showing minimal sealing clamping.
Cosworth also benchmarks other aftermarket head gaskets. This popular brand has better clamping than stock as you can see by the thicker red band. Things could be better, the band is back from the cylinder and is uneven.
The Cosworth gasket has wide even pressure right around the bores. This is the best of the three. Cosworth was out blow out resistant gasket of choice for this project.
To prevent this, we changed the water flow around to mimic what Nissan has done on the latest variants of the VQ engine, the VQ35HR and the VQ37VHR. In these engines, the water comes up from the block around each individual cylinder by the hotter exhaust valves and then out to the radiator. This is done by using the head gaskets for these engines. The blocks water passages must also be enlarged in the area near the bores so the passages in the new gaskets line up with the ones in the block. The revised water flow significantly improves cooling on older VQ engines, essential for ones seeing higher boost.
Here is how Nick enlarged our coolant passage. As you can see you don’t need to remove a lot of material.
Big Honking JWT C9 cams, just what we needed to extend our powerband out to 8000 rpm. These had a serious lope at idle even with the overlap killing variable valve timing of the Rev Up motor.
The cylinder head had to be modified to clear the big lobes of the C9 cams.
Since we wanted a wider and higher powerband, JWT supplied us with a set of their biggest C9 camshafts and high performance valve springs. The C9 cams have an intake and exhaust duration of 283.5 degrees, 11.5 degrees more than the C8R cams we were running previously. The lift was a whopping 0.516 up from the older cams 0.473. These are big cams that should give us the thousand rpm more we need in our powerband. The cams are so big that the lifter bucket holes and the sides of the head near the cam lobes must be ground to clear the lobs as they turn! So as we rounded up parts, Nick gave the block’s bores a light honing, enlarged the water passages, touched up the valve job, clearanced the head for the cam lobes and cleaned everything.
Nick ground the head casting on the sides of the lifter bucket boss and on the side of the casting as well to clear the cam lobe.
You can see how close the lobes are here. The C9’s are the biggest VQ cams on the market.
On any turbocharged motor, pistons are probably the most important component. Since we didn’t have any time at all, we had to go with a company that had a proven design sitting on a shelf. We would have preferred to spec something trick for one of our builds but there was simply no time. After seeing what was immediately available, we settled on JE pistons. We are very familiar with JE’s engineering prowess. JE is also an ISO 9000 certified company which means they consistently deliver OEM world class levels of engineering and quality. An ISO 9000 certification is exceedingly difficult to earn, especially for a performance parts company and JE is one of a handful of performance companies we know that, like KW suspension, has joined this elite club.
The ports, valves, combustion chamber and valve job are completely stock. Making power is not a problem with the VQ and we didn’t need to do expensive head work to get more than enough power for what we wanted to do.
JE’s standard bore VQ35 turbo piston is designed for a bore of 95.5 with the proper 0.005” piston to wall clearance built in. JE is capable of holding very tight production tolerances so it is fine to install them with just clean up honing for ring seating. The pistons are machined from a forged 2618 low silicon alloy blank. 2618’s low silicon content makes the alloy much tougher and ductile than high silicon forged and cast pistons. This toughness is very desirable for a turbo piston and competition use. The only drawback to 2618 over cast and high silicon forgings is that it expands more with heat and thus must use a wider piston to wall clearance. High silicon forged pistons can run clearances of 0.003” of an inch and stock cast pistons can run as tight as 0.0006”. Really about the only disadvantage running a larger clearance means is that the engine will rattle more when cold, possible use a little more oil and have slightly less ring and bore life. None of this really matters in a really high performance motor where the strength is the most important aspect.
We upgraded our cam followers to the HR engine’s DLC coated lightweight forged steel cam followers. The valve clearance is controlled by this little pedestal on the underside of the follower. You can buy different heights of these followers from Nissan to adjust valve clearance. Nick faced off these to set our valve clearance.
JE forged pistons are made of tough 2618 low silicon aluminum alloy. This alloy is tougher than typical high silicon alloys found in cast and some forged pistons. Low silicon aluminum expands more with heat so they must run wider clearances. Even with wider clearances the pistons run clatter free. The lustrous look is due to WPC treatment. WPC helps lubrication and reduces wear. We WPC treated the pistons, piston pins and rings.
The pistons are designed with a full round skirt with JE’s turbo cam profile to just about eliminate the possibility of scuffing. The turbo cam shape is more pronounced as the crown of the piston is subjected to more heat under boost and will grow more. The dome volume is -12.6 cc which should give a turbo friendly compression ratio of 8.5:1 with a 0.63mm head gasket. The piston pin is a thick wall steel part to prevent flexing, a problem that can hurt the small end of the rod with a boosted motor. The piston comes drilled with double pin oilers. These are passages from the oil ring grooves to the pin bores. Oil scraped off of the cylinder walls by the oil rings is then pressure fed to the pin, a nice feature. The complete piston weighs in at a lightweight 380 grams.
The JE piston has a dish to give a compression ratio of 8.5:1. The grooves around the top of the piston above the first ring groove are anti detonation grooves. They help control expansion around the top of the piston to reduce the odds of scuffing and act like a shock wave buffer to reduce pressure spikes to the rings.
JE gives the piston top generous radii so nothing will need deburring, speeding preparation time. This also helps improve flame travel for better combustion. The number one ring land also features anti detonation grooves. These serve two purposes. First, if the piston top gets really hot and expands, the grooves give the material an area to expand into so the overall piston diameter grows less. This helps reduce scuffing in this area. Second, the grooves act like a baffle, helping to dissipate the pressure waves that detonation can produce, buffering the rings from it. This can help reduce ring flutter. The pistons are machined for a thin low tension ring package, 1.2 mm for the two compression rings and 2.5 mm for the oil control ring. The thin lightweight rings will have less friction and will seal better at high rpm. The top ring has a chrome face while the second ring is nitrided for low friction and longer life.
These holes in the pin bore are dual pin oilers. The holes go to the oil rings where oil scraped from the cylinder walls is fed to the pin bore to help lubricate the pin. The slot between the holes is a reservoir for the oil.
With no time for coatings and other tricks we normally use, we took the pistons to WPC to have them rush treated. WPC is the Japanese micro shotpeening treatment we use on many of our engine projects. WPC bombards metal parts with microscopic special media at hypersonic speeds which refines the metal’s grain on the surface and imparts compressive stress which improves surface hardness, fatigue strength and lubricity to a large degree. We WPC treated the pistons, rings and piston pins. The WPC process should greatly reduce scuffing, which we figured might be important for an engine that would literally have no break in time and reduce friction. For more on how WPC works click here.
The under crown details of the piston show that the forging is pretty close to net shape for minimal weight. Look at all the smooth radii and graduated contours of the interior. These are signs of a thoroughly stress analyzed design.
The ring set uses lightweight and thin low tension rings for low friction and minimal ring flutter. The piston pin is a thick walled steel part. Thin pins flex with turbo engines and can spin or damage the small end rod bushing. We WPC treated the pin, rings and piston for long life and reduced friction.
The next most important item for a high powered engine is the connecting rods. Again we had to choose something that we could get immediately which meant shelf parts. Unfortunately our rod of choice from Cosworth had just gotten discontinued due to poor sales, so we chose K1 Technologies. K1 Technologies is a high quality rod. The K1 rod is an H beam profile designed, finished and machined in the USA.
With heat treated 4340 forged billets, super close tolerance for dimensions and weight and shotpeening for good fatigue strength, K1 Technologies rods are an awesome value.
The rod itself is machined from a forged 4340 steel billet. 4340 is a heat treatable alloy steel similar to chrome molly, having nickel, chromium and molybdenum as alloying agents to give it roughly double the strength of regular steel with a higher nickel content making it stronger and tougher with a higher impact resistance. These properties make 4340 an ideal alloy for connecting rods. The rod is first machined then solution heat treated. This heat treating greatly improves the mechanical properties such as tensile strength of 4340 steel. Solution heat treating makes the alloy homogeneous where all of the atoms in the material effectively become a solid solution during the treatment making the alloying elements evenly distributed around the part.
The rods small end is bronze bushed and the rod machined so the sizing can be held to plus or minus 0.0001 and the weight within one gram per end. Those are exceedingly tight tolerances! After treatment the rod is shotpeened which can improve fatigue strength by over 100%. Another cool feature is the use of high strength 200,000 psi ARP 2000 rod bolts. These premium bolts have asymmetrical threads for more thrust engagement for better torque consistency.
The highly stressed rod bolts are usually the weakest part of any rod and the K1 rods do not skimp here one bit. K1 chose 3/8″ ARP 2000 high strength bolts, at 200,000 psi, they are among the best you can get.
The K1 rods use a beefy 3/8 inch bolt and weigh only 528 grams, almost 100 grams lighter than stock. Less reciprocating weight on our pistons and rods mean less stress on the crank and bearings. These rods should easily take our needed 8000 rpm and our anticipated power levels without breaking a sweat. A call was made to K1 and a set of rods was shipped out to us from Michigan via next day air.
With our pistons and rods handled, it was time for the rest of the bottom end to be addressed. We turned to Cosworth for our engine bearings. We used std size Cosworth rod and main multi layer bearings. A multi layer bearing can have the embedabilty of a soft bearing which is good for preventing damage to the crank in case of slight contamination with the load bearing capacity of a harder bearing.
Cosworth rod bearings have a lot of crush clearance and thick heat treated springy shells for better spin resistance. The overlay is thinner with no flash zinc for less heat retention and lower surface friction.
Cosworth bearings have a hardened steel backing which helps make for a more spin resistant and resilient bearing. When combined with greater crush clearance the bearings will be retained in the rod and main cap better. The bearing overlay is thinner for higher load capacity and cooler running and less friction. The main bearings have grooving over ¾ of the surface instead of the more common ½ for better oil distribution to the rods. Finally the flash zinc plating of the overlay is eliminated for improved heat transfer. Cosworth bearings can take over 1000 hp so they should hold up well in our application.
The Cosworth main bearings have the same features as the rod bearings and most notably have a 3/4 circle groove that feeds the rods. Typical main bearings have 1/2 grooved bearings. The 3/4 grooved mains feed the rods better.
Next we got a set of Cosworth head gaskets with the HR water flow pattern. The Cosworth gaskets are a multi layer steel design made from three layers of die cut stainless steel. Die cutting is more precise than the common laser cutting and produces smooth edges. The layers are coated with a 0.25 micron thick layer of nitrile rubber to help with sealing. Most importantly the Cosworth gasket has a folded stopper layer around the cylinder bores for vastly improved sealing and blow out resistance. The Coswoth gasket has much more blow out resistance than the stock Nissan gasket. We got the 0.6mm thickness which is very slightly thinner than the design thickness of our pistons but we figure that this will not be a problem at all.
The Cosworth oil pan baffle has these rubber one way trap doors that keep oil around the pickup during cornering.
Finally we got Cosworth’s oil control baffle. The baffle will reduce the amount of oil sloshing away from the pickup under hard cornering forces. The baffle is made from stainless steel and has rubber trap doors to keep the oil from escaping around the pickup. This should help greatly as drift cars can pull pretty high G’s while being driven.
The oil can flow this way through the baffle but not backwards.
One of the cool features that the VQ35DE has are these piston squirters. These help keep the pistons cool under boost by spraying oil under the crown. These are standard equipment.
With all the parts in hand Nick Hunter assembled our engine and verified all of our clearances in one day. When assembling the engine, Nick used VQ35HR head bolts. These bolts are much stronger at a Rockwell hardness of 36C vs the old bolts 26C. The HR bolts also have three more engaged threads. The HR bolts have a higher torque setting and increased clamp when combined with our Cosworth gaskets should end our sealing problems.
This girdle helps greatly stiffen the bottom end by tying in all of the main caps, helping the VQ take turbo boost with no problem.
With our engine assembled, we got a few more goodies to help our vehicle out. Koyo sent us their latest high fin density radiator. This radiator is a direct drop in fit for the 350Z. Our car already had a Koyo Heavy Duty race radiator but this latest radiator is designed for Z’s that have forced induction, improving cooling with an increased fin count.
The VQ crank is fully counterweighted, has generous overlap and nice fillets making it just about bulletproof for boosted applications. Nick used plenty of assembly lube to help keep things good under initial start up.
JWT reflashed our ECU to raise the rev limit to 8000 rpm and to their best guess of what the tuning should be based on similar engine combinations to ours. Since we were not going to be able to actually tune our engine perfectly, we also obtained an AEM water methanol injection system for absolutely quelling any chances of detonation that might arise. We used a dual nozzle system for the delivery of additional water/methanol mixture. We spent the last few hours of the third day crating up our engine and delivering it to our freight forwarder to ship it to Qatar. With fingers crossed, we got ready for the last stop of our adventure, on to Qatar.