27-01-2014, 11:43 PM
I've heard of DHXs having 8v HDi sized rods, but I think this is one of those incremental changes, so you can't attribute them to one engine. I think probably the DHYs did at some very late points, the DHX and DHY are two totally different engines in terms of control and features but produced in the same era.
Both DHX and DHY have a coating on the piston crowns to prevent heat transfer and on the skirts for friction reduction and the heads will have the steel inserts between valve seats to prevent cracking.
D8As seemingly threw less rods than DHYs, but I've seen both throw in stock and tuned applications, I've also seen DHXs pop rods as I've also seen 8v HDis pop rods - none are infallible. DHXs seem to do it less, but the chance is always there - but on the same token I've seen DHYs put up with incredible amounts of abuse, yet D8As barely spool the turbo then pop.
K14/T2 exhaust manifold does seem to flow better, but a GT15 one will spool turbos faster - higher gas velocity, closer to the head etc. Go look at Antos dyno result with a TD04 on a GT15 manifold - one of the higher powered TD04 engines, still on a GT15 mani - a T2 would eventually produce higher figures.
"Xantia" inlets i.e. front mount IC inlet manifolds - there is NO such thing as a non-egr Xantia inlet - some do have a cap over the EGR inlet port, but have all the stuff inside ready. At least, to this day I've never seen one.
Basically:
D8A - Two types - old style with old lucas pump or for a time, Bosch VE, no EGR, no cat and old design cylinder head, no piston coatings. Newer style had updated Lucas pump, early EGR and a Cat - they're rare though.
D8B - Newer engine design for 406/Xantia - Bosch VE only with shield over solenoid, FMIC "Xantia" inlet, has updated design of the later D8A which included a Cat, early EGR and coatings inside the engine.
DHY - Newer design to replace D8A, has a coded, newer design Lucas pump (shield over solenoid), EGR, Cat, coatings inside.
DHX - New design for later 406s and Xantias and various vans - Only a Bosch VP21 pump (ECU Controlled advance system), variable EGR, Cat, coatings on internals.
From what I understand, the DHX and DHY were to conform to new emissions standards, they are simply lightly updated designs of the D8* engines. The D8* engines really are a mish mash of bits, from DH* things conform a bit better.
Both DHX and DHY have a coating on the piston crowns to prevent heat transfer and on the skirts for friction reduction and the heads will have the steel inserts between valve seats to prevent cracking.
D8As seemingly threw less rods than DHYs, but I've seen both throw in stock and tuned applications, I've also seen DHXs pop rods as I've also seen 8v HDis pop rods - none are infallible. DHXs seem to do it less, but the chance is always there - but on the same token I've seen DHYs put up with incredible amounts of abuse, yet D8As barely spool the turbo then pop.
K14/T2 exhaust manifold does seem to flow better, but a GT15 one will spool turbos faster - higher gas velocity, closer to the head etc. Go look at Antos dyno result with a TD04 on a GT15 manifold - one of the higher powered TD04 engines, still on a GT15 mani - a T2 would eventually produce higher figures.
"Xantia" inlets i.e. front mount IC inlet manifolds - there is NO such thing as a non-egr Xantia inlet - some do have a cap over the EGR inlet port, but have all the stuff inside ready. At least, to this day I've never seen one.
Basically:
D8A - Two types - old style with old lucas pump or for a time, Bosch VE, no EGR, no cat and old design cylinder head, no piston coatings. Newer style had updated Lucas pump, early EGR and a Cat - they're rare though.
D8B - Newer engine design for 406/Xantia - Bosch VE only with shield over solenoid, FMIC "Xantia" inlet, has updated design of the later D8A which included a Cat, early EGR and coatings inside the engine.
DHY - Newer design to replace D8A, has a coded, newer design Lucas pump (shield over solenoid), EGR, Cat, coatings inside.
DHX - New design for later 406s and Xantias and various vans - Only a Bosch VP21 pump (ECU Controlled advance system), variable EGR, Cat, coatings on internals.
From what I understand, the DHX and DHY were to conform to new emissions standards, they are simply lightly updated designs of the D8* engines. The D8* engines really are a mish mash of bits, from DH* things conform a bit better.
