3400/3500 Hybrid Parts

The LX9 3500 gives 3400 owners an excellent upgrade path, but also introduces more confusion.  Here is a simple breakdown to how it all works.  Sorry, 3500 heads should not be used on a 3100 due to the bore/combustion chamber overlap.

Using 3500 heads on a 3400 lowers compression to about 9:1 on a stock bottom end 3400.  Pushrods, valve springs, retainers, keepers, and valves are all compatible.  8mm rocker arms are the only option for the 3500 heads, so for those with 96-02 3400, you will need the 8mm rockers to do the swap.

The 3500 lower intake must be used with the 3500 heads.  The coolant temp sensor is no longer located in the lower intake, but rather the rear head instead.  Drilling and tapping for the stock location is 1 option, along with plugging the rear head like the front head is plugged.  The other is to extend your coolant temp lines and use a coolant temp sensor in the rear head.  This will require a new sensor as the threads are not the same as the 3400 style.

Porting for the upper intake is where the confusion really sets in.  There are 2 gasket sizes available, the 3400 sized paper gasket, and the 3500 sized metal (or felpro paper of the same size found in the metal lower gasket set).  The 3400 upper intake should not be ported for this larger size, as it is much larger than can be properly ported.  The larger size increases flow, but requires the 3500 upper to be ported to this larger size as well.

The 3500 upper requires grinding to clear the fuel pressure regulator, and the 3500 swap FPR bracket helps with this as well (otherwise it is a fine line between clearing, and grinding a hole through the upper).  The cannister purge will no longer bolt up to the 3500 upper, the DIS mounting bracket won't line up, and the stock 3500 purge location needs to be tapped for a vacuum line.  For these reasons, the 3400 upper intake is the recommended route to take.  With the 3400 upper, everything else bolts up like stock.

The advantage of the 3500 upper is a broader powerband and not necessarily an increase in peak power.  Due to the tube that runs into the middle of the upper, cylinders 5 and 6 see less flow than the rest, while cylinders 3 and 4 see the best flow.  A 2000+ 3400 upper flows almost exactly the same across all cylinders.

The parts below are all designed for using the 3400 size gasket, even the 3500 upper intake.  If you want to use the larger port size, please check the 3500 section of the site.

Image	Name	Price
	Sportsman Ported 3500 Upper Intake Using a 3500 upper intake on a 3400 improves the powerband of your engine, and porting the manifold improves flow significantly.  This manifold is matched for use with either the sportsman or competition series 3400 lower intake manifold.  Unlike the competition series, the ports are strai…	$59.99
	Competition Ported 3500 Upper Intake Using a 3500 upper intake on a 3400 improves the powerband of your engine, and porting the manifold improves flow significantly.  This manifold is matched for use with either the sportsman or competition series 3400 lower intake manifold.  The Competition series has a radiused entrance at …	$79.99
	Sportsman Ported LX9 3500 Lower Intake for 3400 Upper Intake Based on the same porting as the competition series, this 3500 lower is designed for the 3400 upper intake, or 3500 upper with 3400 sized port.  The runners are matched for the upper and heads and blended to the middle portion of the runner.	$99.99
	Competition Ported LX9 3500 Lower Intake for 3400 Upper Intake The stock 3500 manifolds are excellent in design, but are also restrictive from the factory. WOT-Tech manifolds have been flow tested and dyno proven (without tuning to date). Below are the numbers for a stock set of heads/manifolds, with a WOT-Tech ported 3500 head and stock manifolds to show the d…	$134.99
	AN-6 fittings for 3X00 fuel rails These  AN-6 male end fittings are made from aluminum and then anodized red to protect the finish.  These fittings will allow you to use a remote FPR and braided hoses.  Price is for the fittings only, no hoses or fuel pressure regulator. These pictures are of the now discon…	$39.99
	3500 Swap FPR Bracket          When doing the 3500 top end swap, or a complete 3500 swap into an older vehicle, the 3x00 fuel rail can be used with this bracket to keep your stock fuel system.  The 3500 fuel rail is a returnless setup, unlike the older systems that use a return line…	$34.99
	Sportsman Ported 3500 Cylinder Heads Only available from 2004-2006, these non VVT heads are a huge step forward for what is likely the last revision compatible with the 3400 engine. These will not fit the 2.8, 3.1, or 3100 engines due to the combustion chamber size vs the bore of the engine.   These cylinder heads are our an…	$349.99